|
![]() |
|
| UFDC Home |
myUFDC Home | Help | RSS
|
|

HIDE
| Title Page | |
| Transmittal letter | |
| Contents | |
| Abstract | |
| Introduction | |
| Hydrologic system | |
| Water resources | |
| Summary | |
| References | |
| Appendix | |
| Copyright |
CITATION
SEARCH
THUMBNAILS
DOWNLOADS
PDF VIEWER
PAGE IMAGE
ZOOMABLE
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Full Citation | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
STANDARD VIEW
MARC VIEW
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Downloads | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Table of Contents | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Title Page
Page i Page ii Transmittal letter Page iii Page iv Contents Page v Page vi Page vii Page viii Abstract Page 1 Page 2 Introduction Page 3 Page 4 Page 5 Hydrologic system Page 6 Page 5 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Water resources Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 15 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Summary Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 47 References Page 55 Page 56 Appendix Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Copyright Copyright |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Full Text | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
STATE OF FLORIDA DEPARTMENT OF NATURAL RESOURCES Randolph Hodges, Executive Director DIVISION OF INTERIOR RESOURCES J.V. Sollohub, Director BUREAU OF GEOLOGY Robert 0. Vernon, Chief Report of Investigations No. 57 EVALUATION OF THE QUANTITY AND QUALITY OF THE WATER RESOURCES OF VOLUSIA COUNTY, FLORIDA By Darwin D. Knochenmus and Michael E. Beard U.S. Geological Survey Prepared by UNITED STATES GEOLOGICAL SURVEY in cooperation with the FLORIDA DEPARTMENT OF NATURAL RESOURCES DIVISION OF INTERIOR RESOURCES BUREAU OF GEOLOGY and the BOARD OF COUNTY COMMISSIONERS OF VOLUSIA COUNTY TALLAHASSEE, FLORIDA 1971 DEPARTMENT OF NATURAL RESOURCES REUBIN O'D. ASKEW Governor RICHARD (DICK) STONE Secretary of State THOMAS D. O'MALLEY Treasurer FLOYD T. CHRISTIAN Commissioner of Education ROBERT L. SHEVIN Attorney General FRED 0. DICKINSON, JR. Comptroller DOYLE CONNER Commissioner of Agriculture W. RANDOLPH HODGES Executive Director LETTER OF TRANSMITTAL Bureau of Geology Tallahassee September 23, 1970 Honorable Reubin O'D. Askew, Chairman Department of Natural Resources Tallahassee, Florida Dear Governor Askew: The Bureau of Geology, Division of Interior Resources, Department of Natural Resources, is publishing as its Report of Investigations No. 57, an "Evaluation of the Quantity and Quality of the Water Resources of Volusia County, Florida." This report amplifies and refines some of the data already issued covering the water resources of Volusia County, which were published as Report of Investigations No. 21. The work in the report was accomplished as a cooperative program between the Department of Natural Resources, the U. S. Geological Survey and the Board of County Commissioners of Volusia County. Volusia County is almost totally dependent upon the water which falls upon the county and has a recharge area contained along the western portion and the central portions of the county. Excellent water is produced in the areal recharge and it is anticipated that this data will expand the existing knowledge of the water resources to permit the development of a great capacity for existing utilities and to offset and solve some of the problems now in the area. Sincerely yours, R. 0. Vernon,Chief Completed manuscript received November 3, 1970 Printed for the Florida Department of Natural Resources Division of Interior Resources Bureau of Geology by Designers Press Orlando, Florida Tallahassee 1971 iv CONTENTS Page .. 1 .. 3 Abstract ...................................... Introduction ................................... Purpose and scope ........... Acknowledgements .......... Hydrologic System .............. Physiography ............... Hydrogeology ............... Recharge to Floridan aquifer Rainfall ................... Water Resources ................ Surface Water ............... Lakes .................. Streams ................ Ground Water ............... .............................. 3 ......................... 5 ..................... .. 5 ................... ....... 5 ............ ............. 8 . . . . . .. . 10 ........................ 13 ........................ 15 ........................ 16 ........................ 16 .............................. 19 ......................... .... 31 Clastic aquifer ............. Floridan aquifer ........... Springs .................. Water availability and use ........ Summary ........................ References cited .................. Appendix ....................... ......I ......I ...... ...... ILLUSTRATIONS Figure Page 1. Map of Volusia County Showing the location of hydrologic data-collection sites ................................ 4 2. Physiographic features of Volusia County ........................ 6 3. Topographic map of Volusia County ............................ 7 4. Fence Diagram of hydrogeologic sections in Volusia County ................................................... 8 5. Block diagram of part of Volusia County showing the movement of water ..................................... 10 6. Hydrographs of water levels in wells at hydrologic data sites 14,23, and 25 ..................................... 11 7. Monthly and annual rainfall at Daytona Beach Airport and DeLand ...................................... 14 8. Hydrographs of daily stage for four lakes in Volusia County ........................................... 16 9. Flow chart of streams in Volusia County ........................ 21 10. Water surface profiles of Deep Creek (Osteen) for high and low discharges ..................................... 22 11. Flow duration curves for major streams in Volusia County ................................................... 24 12. Hydrographs of temperature, specific conductance, streamflow, and rainfall for Deep Creek near Osteen, 1965 ............................................. 27 13. Dissolved solids duration curve for Deep Creek near Osteen .............................................. 28 14. Chemical analyses of selected composites of samples from Deep Creek near Osteen showing relative proportions of major mineral constituents .............................................. 30 15. Volusia County showing contours on the piozometric surface of the Floridan aquifer ...................... 34 16. Hydrographs of long-term records of ground-water levels in the Floridan aquifer near Barberville and Daytona Beach ........................................ 36 17. Total dissolved solids in ground water from upper part of Floridan aquifer in Volusia County ...................... 38 18. Total hardness of ground water from upper part of Floridan aquifer in Volusia County ............................ 39 19. Chloride content of ground water from upper part of Floridan aquifer in Volusia County .......................... 41 20. Relation of chloride concentration to discharge at Ponce de Leon Springs ...................................... 44 21. Graph of water use in Volusia County, 1950-1970 ................. 46 22. Map showing location of well fields ............................ 50 TABLES Table Page 1. Comparison of chemical analyses of Lake Winne- missett and Lake Dupont .................................... 18 2. Drainage areas, average flows, and low flows of subbasins in Volusia County .................................. 20 3. Selected chemical characteristics of surface waters in Volusia County .................................... 25 4. Comparison of ground water quality at various depths in Volusia County .................................... 33 5. Chemical analyses of springs in Volusia County ................... 42 6. Water use in Volusia County ............................... 48-49 7. Chemical analyses of public water supplies ....................... 53 8. Hydrologic data-collection sites in Volusia County and vicinity .............................................. 57 EVALUATION OF THE QUANTITY AND QUALITY OF THE WATER RESOURCES OF VOLUSIA COUNTY, FLORIDA by Darwin D. Knochenmus and Michael E. Beard ABSTRACT Volusia County includes about 1,200 square miles along the central east coast of Florida. The population of the county increased by 60 thousand people between 1955 and 1965. Water use in 1967 averaged about 25.9 mgd (million gallons per day), of which the major use (15.8 mgd) was for public supply. In the 20-year interval, 1950 to 1970, the amount of water used for public supply, all of which is ground water, will have more than doubled. On the average, it is estimated that 300 mgd is available for man's use. Ninety-five percent of the water used in Volusia County comes from the Floridan aquifer. The county receives most of its fresh water from rainfall, which averages 52 inches per year. The unconsolidated sand of the clastic aquifer absorbs much of the rainfall. Seepage from the clastic aquifer is to streams and to the underlying Floridan aquifer. Recharge to the Floridan aquifer occurs throughout the county wherever the water table in the clastic 'aquifer is higher than the piezometric surface in the Floridan aquifer. No area is a principal recharge area, but parts of the ridges and the eastern part of the Talbot terrace appear to have the greatest recharge per unit area. In the central part of the county the clastic aquifer is full and rejecting recharge through runoff and evapotranspiration. If the piezometric surface were lowered in this area by withdrawing water from the Floridan aquifer for use, this rejected recharge would be decreased by the capture of water. This would increase the amount of water available for use. Of the few hundred lakes in the county, most occur along the DeLand ridge, where there are about 120 larger than 5 acres. Many of the ridge lakes, because of their size, purity, and small range in surface level fluctuation have excellent recreational potentials. Water in most lakes in the county has a low mineral content with mineral- ization ranging from slightly less than 25 to 150 mg/1l (milligrams per liter). Streamflow out of the county averages about 590 mgd. Flow into the Atlantic Ocean is about 225 mgd and the St. Johns River BUREAU OF GEOLOGY receives about 365 mgd. The average streamflow is many times larger than the water use for the entire county, but is adequate as a water supply because of the variation in flow. During low-flow periods, streamflow averages less than 5 mgd. The mineralization of the water in the streams is relatively low with the exception of the St. Johns River and the estuarine sections of Tomoka River and Spruce Creek along the Atlantic coast. Under average flow conditions, the mineral content of the water is less than 200 mg/1, the pH about 6 and the color about 300 platinum-cobalt units. The productive Floridan aquifer underlies the entire county. Movement of water in the aquifer is outward from the central part of the county, west, north and south to the St. Johns River and east toward the Atlantic Ocean. Water levels were slightly higher in 1966 than in 1955, but show no upward or downward trend except in heavily pumped areas. In one such area near Daytona Beach, water levels have declined more than 5 feet since 1955. Mineral content of water from the Floridan aquifer ranges from 100 to 400 mg/l except in the highly mineralized areas along the St. Johns River and the Atlantic coast. Most high capacity wells in the county withdraw water from the Floridan aquifer for the public supply of areas near the Atlantic Ocean and the St. Johns River. The relatively shallow presence of saline water in these areas limits useful well depths to about 300 feet. Such wells, however, generally yield 1,000 to 1,500 gallons per minute. The depth to saline water in the undeveloped central part of the county is as much as 1,450 feet; thus development of deeper wells in that area should result in higher yields because of the greater available thickness of fresh water in the aquifer. Such development would also have the added desirable effect of capturing recharge water that is currently rejected and lost to the area by runoff and evapotranspiration. The Floridan aquifer discharges water through large springs along the St. Johns valley. Blue Springs, the ninth largest spring in Florida, has an average flow of 105 mgd and Ponce de Leon Springs has an average flow of 20 mgd. This large volume of water however, is generally unsuitable for public supply. The chloride content of Blue Springs is always greater than the 250 mg/l limit suggested by the U. S. Health Service. During periods of high discharge, Ponce de Leon Springs also exceeds the suggested chloride limit. REPORT OF INVESTIGATION NO. 57 INTRODUCTION Volusia County, an area of 1,200 square miles, is located along the central east coast of Florida, figure 1. In 1965, it ranked fif- teenth in rate of growth of the state's 67 counties. The population in 1965 was 157,900, an increase from 1955 of about 60 thousand (Florida Development Commission, 1965). The county's population is expected to continue to increase, causing a commensurate increase in water use. The greatest water use, at present, is along the coast where nearly 60 percent of the population resides. PURPOSE AND SCOPE In 1960, a report on the ground-water resources of Volusia County was published by the Florida Geological Survey (Wyrick, 1960). This report, based on an investigation made during the mid-1950's, provided a base for an understanding of the complex hydrologic system within the county but also raised a number of pertinent questions. To further consider these questions and expand the scope of the earlier study to include surface waters and attendant drainage problems, a 3-year investigation of the water resources of Volusia County was begun in August 1964 by the U. S. Geological Survey in cooperation with the Board of County Commissioners of Volusia County and the Bureau of Geology, Florida Department of Natural Resources. This investigation was intended to: (1) Define the primary areas of recharge to the Floridan aquifer, including the rate and quantity of downward movement of water from the clastic aquifer to the Floridan aquifer and describe the hydrologic system in terms of the effects of physiography, hydrogeology, and rainfall on the occur- rence, quantity and movement of water; and (2) evaluate the sur- face-water resources of the county with respect to quantity, quality, drainage characteristics and surface drainage feasibility. The accom- plishment of the above should provide a more comprehensive scien- tific basis for optimum development of the county's water resources. To accomplish these objectives, a series of test wells was.drilled and hydrologic data from throughout the county were collected and analyzed. Figure 1 shows the locations where hydrologic data were collected on a periodic basis. Descriptions of the sites and types and periods of record are given in table 8 in the Appendix. Miscellaneous hydrologic data were collected at numerous other sites. During the investigation climatic conditions varied from extremely wet to BUREAU OF GEOLOGY 1? .2a, EXPLANATION HYDROLOGIC DATA SITE & STREAM 0 WELL O LAKE o SPRING I DATA SITE NUMBER ON TABLE 8. [ I Figure 1. Map of Volusia County showing the location of hydrologic data- collection sites. -REPORT OF INVESTIGATION NO. 57 extremely dry which permitted observation of the hydrologic system under a wide range of conditions. This report describes the hydrologic system with reference to the movement of ground water from the clastic aquifer to the Floridan aquifer. The two aquifer systems are described and the influence of geologic faulting on the quality of water in the Florida aquifer is discussed. Surface waters are discussed in terms of the quantity and quality of water in lakes and streams. Water-use trends are predicted for public supply, irrigation, industrial and rural uses. Only minimal information about the St. Johns River is included in this report as a more detailed description of the water resources of the St. Johns is given by L. J. Snell and Warren Anderson (1970). A report, discussing surface drainage characteristics has recently been published as a result of this investigation (Knochenmus, 1968). Conjunctive use should be made of that report and the current report to provide the basis for optimum water resource development in Volusia County. ACKNOWLEDGMENTS Appreciation is extended to the many people of Volusia County who supplied information for the investigation. Thanks are due Thomas Well Drilling Company and Mr. Roger Brooks who supplied information about wells and quality of water and to the city officials who furnished information on municipal water use. Thanks are also extended to county officials, who cooperated in all aspects of the investigation. HYDROLOGIC SYSTEM The various environments on, above, or beneath the land surface through which water moves constitute a hydrologic system, and the circulation of water through these environments is known as the hydrologic cycle. The ultimate source of water used by man is rainfall, although water may move into any given political division, such as a county, from outside its boundaries through streams or by underground flow. In Volusia County most of the fresh water in the hydrologic system has originated as rainfall on the County. PHYSIOGRAPHY The topography of Volusia County has been described by Wyrick (1960). A generalized picture is of a succession of terraces BUREAU OF GEOLOGY EXPLANATION E KARST RIDGES L' MARINE TERRACES 3 SHORELINE RIDGES --PHYSIOGRAPHIC BOUNDARY' Figure 2. Physiographic features of Volusia County. 9o, a -REPORT OF INVESTIGATION NO. 57 extremely dry which permitted observation of the hydrologic system under a wide range of conditions. This report describes the hydrologic system with reference to the movement of ground water from the clastic aquifer to the Floridan aquifer. The two aquifer systems are described and the influence of geologic faulting on the quality of water in the Florida aquifer is discussed. Surface waters are discussed in terms of the quantity and quality of water in lakes and streams. Water-use trends are predicted for public supply, irrigation, industrial and rural uses. Only minimal information about the St. Johns River is included in this report as a more detailed description of the water resources of the St. Johns is given by L. J. Snell and Warren Anderson (1970). A report, discussing surface drainage characteristics has recently been published as a result of this investigation (Knochenmus, 1968). Conjunctive use should be made of that report and the current report to provide the basis for optimum water resource development in Volusia County. ACKNOWLEDGMENTS Appreciation is extended to the many people of Volusia County who supplied information for the investigation. Thanks are due Thomas Well Drilling Company and Mr. Roger Brooks who supplied information about wells and quality of water and to the city officials who furnished information on municipal water use. Thanks are also extended to county officials, who cooperated in all aspects of the investigation. HYDROLOGIC SYSTEM The various environments on, above, or beneath the land surface through which water moves constitute a hydrologic system, and the circulation of water through these environments is known as the hydrologic cycle. The ultimate source of water used by man is rainfall, although water may move into any given political division, such as a county, from outside its boundaries through streams or by underground flow. In Volusia County most of the fresh water in the hydrologic system has originated as rainfall on the County. PHYSIOGRAPHY The topography of Volusia County has been described by Wyrick (1960). A generalized picture is of a succession of terraces REPORT OF INVESTIGATION NO. 57 that begin at sea level and, progressing westward, rise steplike to an altitude of 100 feet at DeLand, and then drop sharply to almost sea level at the St. Johns River, figure 2. A classification of the physiographic features into three divi- sions; karst ridges, marine terraces, and ancient and present shoreline ridges, was adapted from Puri and Vernon (1964). Karst topography, as exemplified by the Crescent City and DeLand ridges, is characterized by high local relief, sinkhole lakes and ponds, dry depressions, and subsurface drainage. Near Deltona the land is over 110 feet in altitude, whereas nearby, southeast of Orange City, depressions dip to 10 feet above mean sea level. This results in relief of about 100 feet on the DeLand ridge. The county has about 120 lakes larger than five acres with 90 percent located within the karst ridges. On the DeLand ridge most of the lakes are along the eastern and southern edges whereas they occur over the entire extent of the Crescent City ridge. More water is cycled through the ground-water system from the karst ridges, with their comparatively high relief and good subsurface drainage, than from areas where surface drainage is better developed. These ridges also act as reservoirs for the storage of surface and ground water until it recharges the Floridan aquifer or evaporates. The marine terraces are poorly drained flat surfaces covered with forest vegetation and are commonly called "flat-woods". Three terraces are shown on figure 2; Silver Bluff terrace at 10 foot altitude, Pamlico terrace at 25 feet, and Talbot terrace at about 40 feet. Numerous swamps and cypress heads occupy shallow depres- sions which had their origin on the ancient sea floor. A topographic map of the county, figure 3, indicates a youthful surface, flat and poorly drained. Surface drainage on marine terraces is in the first stages of development. Knochenmus (1968) delineated the drainage basins, mapped the runoff distribution and indicated feasibility of drainage of the terraces in Volusia County. Figure 3. Topographic map of Volusia County. (In pocket) Streams on the marine terraces generally flow north or south parallel to the coastline. The beach ridges parallel to the coast (fig. 2), which formed during the building of the terraces, prevent the streams from draining directly to the ocean. One stream system, by taking a longer route to the ocean, can drain an area that would have required many short streams. Many short streams flowing into the ocean might have allowed salt water to move inland in numerous BUREAU OF GEOLOGY places, whereas only Tomoka River and Spruce Creek now allow salt water to move inland. The third physiographic division, the shoreline ridge, encom- passes a low ridge on the seaward edge of each of the three marine terraces (fig. 2). Rima ridge is a low sand ridge rising 5 to 10 feet above the Talbot terrace; the Atlantic Coastal ridge rises 10 to 15 feet above the Pamlico terrace; and the present Atlantic ridge rises about 10 feet above the Silver Bluff terrace. Rima ridge and the Atlantic Coastal ridge are ancient shoreline ridges whose depositional history is similar to the deposition of the present Atlantic ridge. The shoreline ridges act as reservoirs for the storage of ground water. The water table beneath the ridges is higher than beneath the adjacent terraces resulting in a more vigorous subsurface circulation and recharge into the limestone in the areas of the ridges. HYDROGEOLOGY The geologic materials of Volusia County comprise two major hydrogeologic units, the upper poorly consolidated clastic deposits and the underlying thick sequence of limestone and dolomite, commonly called the Floridan aquifer; both are shown in the fence diagram of figure 4. Wyrick (1960, p. 25) discussed the two major units in terms of the nonartesian and artesian aquifers. Figure 4. Fence diagram of hydrogeologic sections in Volusia County. (In pocket) The clastic deposits are made up of poorly consolidated sand, clay, and shell of Pleistocene to Miocene age. They occur as discon- tinuous, lenticular, and interfingering beds (fig. 4). The material in any given bed may grade from sand to clayey sand to clay, and the shell beds may have a matrix of sand, clay, or both. In general the surface material is fine sand which is underlain by clay lenses and then by shell beds which in turn overlie the limestone except in a few areas near the coast where clay lenses underlie the shell beds. Under the eastern edge of the Talbot terrace, the sand appears to thicken, and particularly under the Rima ridge the clay is thin or missing (sites 13 and 22, fig. 4). In places the shell beds are as much as 50 feet thick and are comprised of large shells. Permeability is a measure of the ability of a geologic material to transmit water in response to differences in hydraulic head, or gradi- ent. The movement of ground water between the clastic deposits and the Floridan aquifer is controlled by the permeability of the clastic REPORT OF INVESTIGATION NO. 57 deposits and the head differential between the units. Because of the lenticularity and discontinuity of the clastic deposits, the rate of vertical movement of water ranges widely. On the basis of cuttings from a few wells it appears that the variation in vertical permeability is as great from site to site within the same physiographic division as between sites within different physiographic divisions. For example, low permeability beds occur at site 16 (fig. 4) on the north end of DeLand ridge and at site 19 on the Talbot terrace, whereas higher permeability beds were found at site 25 on the south end of DeLand ridge and site 14 on the Talbot terrace. Where a confining bed of relatively impermeable clay or sandy clay overlies the Floridan aquifer, the water in the Floridan aquifer is confined. Locally, in areas downgradient from a topographic high where there is an over- lying confining bed, water in the shell bed and even in the sand occurs under confined conditions. Such areas occur along Highway 44, on the east side of DeLand ridge and on the west side of Rima ridge (sites 21 and 22, fig. 4). The top of the Floridan aquifer dips eastward from its high under the DeLand ridge, toward the coast at about 3 feet per mile. Under the terraces the clastic deposits thicken from 65 feet on the eastern flank of the DeLand ridge to 100 feet at the coast. Under the DeLand ridge where the relief is much greater the clastic deposits are 50 to 100 feet thick. Structually Volusia County is an uplifted fault block (fig. 4). Wyrick (1960, fig. 4) mapped a north-south trending fault west of DeLand and an east-west trending fault on the north edge of Lake Monroe. An extention of a north-south trending fault, mapped by Brown (1962, fig. 9) in Brevard County, cuts Volusia County 5 to 15 miles inland of the coast and completes the fault block. Most of the water supplies in Volusia County are obtained from the limestone and dolomitic limestones of the Floridan aquifer, which in this area is composed of formations of middle and late Eocene age. A hard, dense, irregular layer of dolomitic limestone acts as a confining bed that divides the aquifer into an upper and lower part (fig. 4). This layer is at depths of 150 feet under the DeLand ridge and 250 feet near the coast. The Floridan aquifer is known to be greater than 600 feet thick in the eastern part of the county, based on data from a 700-foot test hole which did not fully pene- trate the aquifer hydrologicc data site 18, fig. 1). A schematic drawing of part of the hydrologic cycle for Volusia County showing the movement of water to and from the surface, on BUREAU OF GEOLOGY the surface, infiltrating the surface, and through the subsurface is shown by figure 5. Figure 5. Block diagram of part of Volusia County showing the movement of water. (In pocket) Water movement on and under each physiographic division follows a somewhat characteristic path. The terraces are character- ized by surface runoff and vertical movement of ground water through the plastic deposits. The ridges are characterized by subsur- face drainage and a vertical as well as horizontal component of move- ment of ground water through the clastic deposits. The water moves laterally through the Floridan aquifer under both the ridges and the terraces but with a component of downward movement near areas of recharge and a component upward movement near the discharge areas (fig. 5). Under the terraces (fig. 5), the water table is near the surface with a relatively thin unsaturated zone available for storage of water during a rise of the water table. Rain quickly saturates the porous surface sand after which the water can no longer infiltrate and must run off or evaporate. The water which has infiltrated moves down- ward to the zone of saturation if not used by plants or retained as soil moisture. As the water moves vertically through the clastic deposits it may follow tortuous paths around discontinuous lenses of less permeable material, and continue in its downward movement into the Floridan aquifer. It then moves laterally toward the east where it discharges to the coastal well fields or to the ocean. As rain falls on the ridges (fig. 5) it infiltrates the sand, and water which is not used by plants or to replenish soil moisture moves down to the water table. The water table generally follows the con- figuration of the land surface. After it reaches the water table, water moves generally parallel to the slope of the water table to ponds or lakes or to low-lying areas where some seeps to the surface to create the swampy conditions adjacent to the ridges. Ground water moves along the slope of the water table and also downward through the plastic deposits to recharge the Floridan aquifer. The movement of water in the Floridan aquifer under the DeLand ridge is westward toward the St. Johns River. Under the low sand ridges movement of water in the Floridan aquifer is eastward toward the coast. RECHARGE TO FLORIDAN AQUIFER A condition where water is confined in an aquifer by relatively impermeable layers is called artesian. The poorly consolidated sedi- ments of the plastic deposits are not highly pervious and tend to REPORT OF INVESTIGATION NO. 57 retard the downward movement of water. Because water does leak down into the Floridan aquifer, however, it is described as a semi- confined artesian aquifer. At many locations there is no geologic evidence of a confining layer and from water level fluctuations it appears as though the Floridan aquifer is hydraulically connected to the overlying clastic deposits. Hydrographs of water levels in wells at hydrologic data sites 14, 23, and 25 are shown on figure 6. The configuration and water level response to rainfall is very similar for 39 'l' M HYDROLOGIC DATA SITE NO 14 S WELL OPEN TO ELASTIC AQUIFER 32 --M WELL OPEN TO UPPER PART OF FLORIDAN AQUIFER----- - 31 D WELL OPEN TO LOWER PART OF FLORIDAN AQUIFER 75 S HYDROLOGIC DATA SITE NO 23 '-S WELL OPEN TO ELASTIC AQUIFER I- 37 3 _. ..HR.....L.OG A I C EoRo DATA SITE NO. 23 AM W E. OPEN TO UPPER PART OF FLORIDAN AQUIFER j j T O A A AU J133 - 24 w -.-o-----.-- i E R P,--- oP---- R,- AN---u-- .---- I ---- --- i--- I--- --- [ --- -- --- ( -- -- -- D WELL OPEN TO LOWER PART OF FLORIDAN AQUIFER " 25 ------ 04 ____ ---- -- ---- --- --- --- -- -- rI.- --- --- --- --- --- -- S WELL OPEN TO ELASTIC AQUIFER I I f ______1_____ Z3 M WELL OPEN TO UPPER PART OF FLORIDAN AQUIFER I .---- I _ D WELL OPEN TO LOWER PART OF FLORIDAN AQUIFER -- .. .. _____ _____ _____ D o i ..... F I- I -- -"--. _" 08 HYDROLOGIC DATA SITE NO. 25 _.___ JAN FEB MAR APR MAY JUNE JULY AUG SEPT I NOV DEC JJAN FEB M APR MAY JUNE 1966 1967 Figure 6. Hydrographs of water levels in wells at hydrologic data sites 14, 23, and 25. the well in the clastic deposits and the well in the Floridan aquifer (data site 14) which indicates a good hydraulic connection between BUREAU OF GEOLOGY the two units. Hydrographs for wells at hydrologic data site 23 indicate a lesser degree of connection while at site 25 there appears to be a good connection, with water moving downward into the upper part of the Floridan aquifer. At site 25, water is also moving upward into the upper part of the Floridan aquifer from below and, therefore, water must be moving laterally through the upper part of the aquifer. Water moves downward into the Floridan aquifer wherever the water table in the clastic deposits is higher than the piezometric surface. Piezometric surface, as used in this report, means the level to which water will rise in tightly cased wells that penetrate the Floridan aquifer. Ridges which rise above adjacent land are capable of supporting a higher water table and this increased head results in greater leakage from the clastic deposits to the Floridan aquifer, assuming equal permeabilities and thicknesses of material. Where the land surface is relatively low, the piezometric surface is near land surface, which results in less recharge and greater surface runoff. In stream valleys and at low altitude along the coast the wells which penetrate the Floridan aquifer will flow. In these areas, where the piezometric surface is above the land surface (see fig. 18, Wyrick, 1960), there is no recharge to the Floridan aquifer. Earlier Wyrick (1960, p. 27 and fig. 14) had reached similar conclusions when he stated that recharge to the Floridan aquifer (artesian aquifer) occurs wherever the water table is higher than the piezometric surface. Wyrick (1960, p. 27 and fig. 13) also indicated that the principal area of recharge to the Floridan aquifer in Volusia County was within the closed 40-foot contour along the eastern edge of the DeLand ridge (Penholoway terrace) near DeLand. But the 40-foot contour of Wyrick's map also encloses the western part of the Talbot terrace, where the piezometric surface is presently at about the level of the water table and in many places rises above it. There are areas outside the 40-foot contour where the hydraulic gradient between the water table and piezometric surface is greater and the permeability is as great, and which are thus better recharge areas. No area in Volusia County can be considered the principal recharge area. Visher and Wetterhall (1967) state that in Florida most piezometric highs indicate areas of low permeability and low or rejected recharge. Similar results were reported by Schneider (1964) in his studies of the carbonate rock aquifer of central Israel. Schneider noted that piezometric ridges appeared to coincide with down-faulted blocks or structural basins, regarded as regions of lower permeability than adjacent regions having lower piezometric levels. REPORT OF INVESTIGATION NO. 57 The data suggest that the piezometric high areas are not principal recharge areas in Volusia County. Under prese-it hydrologic conditions, the most productive recharge areas are the eastern part of the Talbot terrace and the ridges. There is a relatively good hydraulic connection between the clastic deposits and Floridan aquifer under most of the Talbot terrace, with a greater head between the two hydrogeologic units in the eastern part of the terrace than in the western part, resulting in a better recharge area in the former. The western part of the terrace has good recharge potential, provided a sufficient head differential were maintained, either by lowering the piezometric surface or by raising the water table. The ridges are good recharge areas mainly because of their topographic relief. In general, the ridges have as good a hydraulic connection as the terraces, however, along the eastern edge of the DeLand ridge, in the area east of DeLand coinciding with the 40-foot piezometric contour, the clastic deposits have lower permeability. This area of lower permeability is reflected by the line of lakes whose water surfaces stand relatively high above the piezometric surface. The lake level at data site 29 (fig. 1) is as much as 18 feet above the piezometric surface. A greater head compensates for an otherwise lower recharge through the less permeable material. Lakes themselves are probably no better points of recharge than the surrounding lake basin. The lakes are shallow, 20 feet or less in depth, and their bottoms are not incised into the aquifer, therefore, it is the material between the lake bottom and the aquifer that controls the movement of water to the aquifer. Areas of little or no runoff as shown on a runoff distribution map (Knochenmus, 1968) coincide generally with the areas of higher recharge. Areas where the piezometric surface is at or above the water table (discharge areas), exhibit the highest runoff. RAINFALL Local rainfall is the source of Volusia County's fresh-water. The average (normal) annual rainfall on Volusia County for the period 1931-60 was 52 inches, or about 3,000 mgd (million gallons per day), based on records collected by the U. S. Weather Bureau at Daytona Beach Airport and DeLand. Only a small part, about 10 percent, of this water is readily available for use by man. Average annual rainfall of the two stations during the period of record ranged from a maximum of 74 inches in 1953 to a minimum of 38 inches in 1954. This large annual variation in rainfall is shown on figure 7. BUREAU OF GEOLOGY 20 Is cr 15 -J 10 Li. z -5 Cr 5 I- z 0 0 rr \ N _\\- J F M A M J J A S 0 N D J F M A M J J A S 0 N D 1965 1966 80 DeLond overage Daytona Beach overage 54.7 inches 49.9 inches U- t o 0 0 U-) Figure 7. Monthly and annual rainfall at Daytona Beach Airport and DeLand. The period of investigation included a year of dry conditions (1965) and a year of slightly wetter than normal conditions (1966). Although 1966 was an exception, the western part of the county generally receives more rain than the eastern part. For the long term record, the yearly average at DeLand is 4.8 inches more than at Daytona Beach Airport. In 1965, DeLand received 6.5 inches more rain than Daytona Beach Airport, but in 1966 DeLand received 5 C 0J m C 0 REPORT OF INVESTIGATION NO. 57 inches less than Daytona Beach Airport. The five summer months (June-October) generally receive 65 percent of the annual rainfall. The chemical quality of rain varies slightly with weather condi- tions and with industrial and agricultural activities. Generally, rain contains small amounts of dissolved mineral matter and atmospheric gases. The mineral matter is derived from windborne salts picked up from the open sea or from the land. If the salts are from the sea, the chemical character of the rain is somewhat similar to a diluted sea water with NaCl (sodium chloride) being the predominant consti- tuent. In contrast, when the windborne salts originate from the land the chemical character of rain becomes that of a CaHCO3-CaSO4 (calcium bicarbonate-calcium sulfate) type water. The amount of dissolved mineral matter in rain varies with the amount of rainfall. At the beginning of a storm the amount of wind- borne dust is relatively great and the rain washes this dust from the air resulting in higher concentrations of dissolved salts in the precipi- tation. As the storm continues, the dust is removed from the air and the remaining rainfall is lower in dissolved salts content. The average dissolved mineral content of rainfall for Volusia County is probably no more than 25 mg/1 (milligrams per liter). This value is deduced from the dissolved solids content of several small lakes which have small, closed drainage basins and whose source of water is rainfall and seepage from the relatively insoluble surficial deposits within the basin. Additionally the average dissolved mineral content of rainfall at Ocala, in inland central Florida, and at various sites along the west coast of central Florida is generally no more than 25 mg/1. Rainfall is slightly acid because of the solution of atmospheric CO2 (carbon dioxide) in water droplets, resulting in the formation of H2 CO3 (carbonic acid). Also, industrial operations may add gases to the atmosphere which can produce acids when dissolved in water. The median pH value of the rainfall in Volusia County is about 6. WATER RESOURCES The quality and quantity of water in lakes, streams, and aquifers dictates the usefulness of the water from that particular source. Water changes in chemical quality while moving through the several environments that constitute the hydrologic cycle. Many of these changes are significant and studies of them add to the under- standing of the hydrologic system and permit a more comprehensive BUREAU OF GEOLOGY evaluation of the water resources. Therefore, a discussion of the chemical processes which affect water quality in Volusia County is included in the discussions of lakes, streams and aquifers which follow. SURFACE WATER LAKES The numerous lakes of the County act as storage reservoirs for water. Most of the 120 lakes larger than 5 acres are located on the DeLand ridge where they occupy sink holes. The largest is Lake Diaz with a surface area of 700 acres. LAKE WINNEMISSETT I I LAKE HIRES < 43 _ a 43 W 3 0 a. 3 4J -t* LAKE WINONA 16 S^-- y.f -- -- --- -- - LAKE DUPONT A M J J A S 0 N D J F M A M J J A S 0 N D 1965 1966 Figure 8. Hydrographs of daily stage for four lakes in Volusia County. REPORT OF INVESTIGATION NO. '57 Because of their size, purity and small range in surface level fluctuation, a number of lakes on the DeLand ridge have excellent recreational potentials. At the present time, however, they are used mostly for irrigation water supplies. Most lakes are along the eastern edge of the ridge where the highest water table occurs. Hydrographs of four lakes are shown on figure 8. Lake Winona (site 27, fig. 1), at the north end of the DeLand ridge, had a water level fluctuation of 2.3 feet during the period of this investigation. The level of the lake is approximately 5 feet above the piezometric surface of the Floridan aquifer. Lake Hires (site 28, fig. 1), four miles to the south had a fluctuation during the period of 1.8 ft.; its surface is about 7 feet above the piezometric surface. Six miles farther south, Lake Winnemissett (site 29, fig. 1), one of the higher lakes on the ridge had a fluctuation of 1.7 feet and its surface is approximately 18 feet above the piezometric surface. At the south end of the ridge, Lake Dupont (site 30, fig. 1) had the greatest fluctuation of the four lakes (2.9 feet), and it is about at the level of the piezometric surface. The lakes appear to be water table lakes and thus are related to the piezometric surface in the same manner as the water table is related to the piezometric surface. Lake Dupont has, as has the water table in that area (site 25, fig. 6), a better hydraulic connection to the Floridan aquifer than Lakes Winona, Hires and Winnemissett. The greater fluctuations of the water surfaces in Lake Winona and Dupont are probably due to greater fluctuations of the water table in the area surrounding the lakes, which in turn are related to the greater relief in the area. Water in most lakes in the county has a low mineral content with mineralization ranging from slightly less than 25 mg/1 to 150 mg/l. Many of the lakes are in closed drainage basins where urban and agricultural development are minimal. Lake water in this environment usually contains less than 50 mg/1 total dissolved solids and is similar to the quality of rain water. In contrast, some lakes on the ridge area in large actively farmed drainage basins contain water with as much as 50 mg/l dissolved solids and of a different chemical character than other lakes in the county. Table 1 shows chemical analyses from Lake Dupont in a relatively undeveloped area and Lake Winnemissett located in an area of considerable agricultural activity (more than 50 percent of the basin is under cultivation). Lake Winnemissett contains about five times the amount of dissolved mineral matter as Lake Dupont. Pfischner (1968) has shown that the dissolved solids content of lakes in southwest Orange County, Florida, is generally related to the percentage of the lake basin covered by citrus groves. Table 1, Comparison of chemical analyses of Lake Winnemisaett and Lake Dupont. Chemical analyses, in milligrams per liter Lake Winnemissett near DeLand, Fla. (site 29, fig. 1) 5-11-65 0.0 0.00 18 6.3 10 7.5 8 | 61 20 0.0 0.9 128 71 64 230 6.4 5 Lake Dupont near Lake Helen, Fla. (site 30, fig. 1) 5-18-65 00 0.04 1.2 0.9 5.5 0.3 2 4.8 9.5 0.1 0.2 24 6 5 555 5.7 0 REPORT OF INVESTIGATION NO. 57 STREAMS Important aspects in considering a stream as a potential water supply are the quantity, quality, and associated variations in flow and quality of its water, and the storage capabilities of the stream channel. The average rate of flow of the two largest streams wholly within the county, Deep Creek near Osteen (130 mgd) and Tomoka River (100 mgd), is more than the predicted water use for the entire county in 1980, but they are inadequate as a water supply because their minimum flows are so small. Less than 5 million gallons per day flows out of Volusia County in streams during dry periods. From a water use viewpoint, storage facilities would be neces- sary to insure a dependable surface-water supply during minimum flow periods. Natural channel storage is small in the poorly defined channels but large capacity storage reservoirs could be constructed on the swampy flood plains of the streams. Such storage facilities could be an earthen-diked reservoir, shallow in depth with a rela- tively large surface area where evaporation would be at a maximum. Water in the streams comes from direct runoff during rains, flow out of swamps and seepage from ground water. Ground-water seepage and swamp drainage supply base flow during the periods between rains. During dry spells, when swamps desiccate, base flow is supplied entirely by ground water. Most of the ground-water contri- bution to base flow comes from the poorly consolidated clastic deposits. Even in those areas of upward seepage from the Floridan aquifer, particularly in the western part of the county such as Deep Creek near Barberville and the other Deep Creek near Osteen, the chemical quality of the stream water indicates that very little seepage from the Floridan aquifer reaches the stream channels. Water leaves the county in streams at an average rate of about 590 mgd. About 225 mgd flows into the Atlantic Ocean from Tomoka River, Spruce Creek and smaller streams. St. Johns River receives about 365 mgd from Deep Creek (Osteen), Middle Haw Creek, Little Haw Creek, and Deep Creek (Barberville). Streamflow data are given in table 2. The values of streamflow, except those for Spruce Creek, are estimated from continuous discharge records or from periodic discharge measurements. Based on the data in table 6, over 20 times more water flows out of the county than is presently used (see section on water use below) but the variation in flow limits streamflow as a reliable source of water supply. The magnitude of flow of the major streams is shown on figure 9. The highest rate of flow (average 130 mgd) of streams draining the county is from Deep Creek basin (Osteen) a runoff of 17 inches BUREAU OF GEOLOGY Table 2. Drainage areas, average flows, and low flows of subbasins in Volusia County. Drainage area Average flow Low flow Creek basin sq. mi. mgd mgd Deep Creek (Osteen) 157 *130 0.4. Tomoka River 121 **100 .4 Spruce Creek 96 50 .3 Cow Creek 28 50 0 Middle Haw 41 30 0 Little Haw 61 30 0 Deep Creek (Barberville) 39 25 0 Little Tomoka 15 10 0 All Others 225 - * Includes flow of Cow Creek ** Includes flow of Little Tomoka per year. Flow in the St. Johns River at DeLand averages 2,100 mgd far greater than that of any stream within the county. Certain areas of the County, such as the DeLand, Crescent City, Rima, and Atlantic Coastal ridges, have poorly developed surface drainage systems. The runoff from these areas is from 0 to 6 inches per year (Knochenmus, 1968). Profiles of the water surface of Volusia County streams show flat gradients in their upper reaches with steepening gradients down- stream. Two profiles for Deep Creek (Osteen), one at high flow and the other at low flow, during 1966 are given in figure 10. The fluctu- ation of the water surface in the swampy headwaters was less than a foot while the level fluctuated 40 feet near the mouth. Rain falling on the swampy headwaters causes the water surface to rise about the same as the depth of rainfall, whereas downstream the runoff is collected into a definite channel and the water surface may rise many times the depth of rainfall. Stream flood plains in the county are largely flat swampy areas and become inundated almost every year. The poorly incised channels cannot transport the excess water during wet periods so that water ponds in the swamps and inundates much of the area. The floods on most streams were extremely high in 1964. The peak discharges of Spruce Creek and Middle Haw Creek during the floods of 1964 were determined from curves published by Barnes- and REPORT OF egoo 1JSq, INVESTIGATION NO. 57 ao, f0 r/- EXPLANATION Width of stream represents average flow In million gallons per FLOW SCALE 150 mgd 100 mgd 50 mgd Figure 9. Flow chart of streams in Volusia County. , o90, BUREAU OF GEOLOGY // // I\- I/ 0 VII I !/ -g 1/ 0 O 00 IIL II 'I II If II 13A31 V3S NV3W 3AOBV 133.- '30ni1IV Figume 10. Water surface profiles of Deep Creek (Osteen) for high and low dharges. REPORT OF INVESTIGATION NO. 57 Golden (1966) to be greater than 50-year floods, whereas the peak discharges of Tomoka and Deep Creek (Osteen) were greater than 20-year floods. Runoff characteristics of different streams can be compared by analyzing their flow-duration curves, figure 11. Flow-duration curves show the percent of time during which specified discharges are equaled or exceeded. All the curves are similar in shape with the exception of the lower end of the curve for Spruce Creek. The slopes of all the curves are steep indicating little channel storage and ground-water contribution. The high-discharge end represents mostly overland flow (direct runoff) and the low-discharge end represents ground-water seepage. The low end of the Middle Haw curve is very steep, approaching the vertical, which indicates very little ground- water seepage. The Middle Haw Creek basin is flat with a very shallow stream channel; therefore, with a small lowering of the ground-water level, the water-table falls below the stream bed. With no ground-water seepage to sustain base flows, Middle Haw Creek decreases from medium flow to zero flow very rapidly. Streams with steeply sloped duration curves are characterized by maximum flows 100 times greater than median flow (50 percent line on duration curve). Median flows for Spruce Creek, Middle Haw Creek, Tomoka River and Deep Creek (Osteen) are 4.6, 18, 23, and 39 mgd respectively. About 15 percent of the time Middle Haw Creek has no flow whereas about 15 percent of the time Deep Creek has slightly more than 3 mgd flow. The water in streams in Volusia County has widely differing chemical characteristics, depending on the source of the water. Some streams, especially during low flow, receive discharge from the Floridan aquifer by seepage and from flowing wells. In the lower reaches of streams near the coast the chemical quality of the water reflects mixing with highly saline ocean water. The waters range from only slightly mineralized to ocean salinity, from colorless to highly colored, and from acidic to basic. Values of some of the more important water-quality constituents at surface-water data sites (fig. 1) are listed in table 3. Most streams in Volusia County are supplied by direct rainfall, overland flow, and seepage from the clastic deposits. The quality of the water varies not only because the quality of the rainfall varies, but because most of the water has moved over or through the ground, dissolving mineral matter and transporting it to the streams. Mineral matter derived from the breakdown or weathering of organic and inorganic materials, application of fertilizers, and BUREAU OF GEOLOGY 40 -800 400 --- 600 DEEP CREEK 400 NEAR OSTEEN 2 --- 0-/ I-I I I 300 TOMOKA RIVER /NEAR HOLLY HILL 200 100 S\ 80 .40 -- A\ -60 MIDDLE HAW CREEK 40 NEAR BUNNELL SPRUCE CREEK NEAR SAMSULA \ 20 \ --------- 10 Note: Curve for Spruce Creek compute____ 4 -- --from records for bse period, 1952-6 3 -- from the short-term period, 1965 -66 --- __- 2 Note: Curve for Spruce Creek computed .8 .4 from records for bose period, 1952-66.- ----.6 Curves for the other streams adjusted from the short-term period, 1965-66 - to the base period. | - 7 I 1 1 I I1 I I 1,1 \2 I I I I ~ .1 .2 .5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 PERCENT OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCELLED Figure 11. Flow duration curves for major streams in Volusia County. 1 .2 15 19-9 . . .1 1 1 N 1 9 REPORT OF INVESTIGATION NO. 57 inches less than Daytona Beach Airport. The five summer months (June-October) generally receive 65 percent of the annual rainfall. The chemical quality of rain varies slightly with weather condi- tions and with industrial and agricultural activities. Generally, rain contains small amounts of dissolved mineral matter and atmospheric gases. The mineral matter is derived from windborne salts picked up from the open sea or from the land. If the salts are from the sea, the chemical character of the rain is somewhat similar to a diluted sea water with NaCl (sodium chloride) being the predominant consti- tuent. In contrast, when the windborne salts originate from the land the chemical character of rain becomes that of a CaHCO3-CaSO4 (calcium bicarbonate-calcium sulfate) type water. The amount of dissolved mineral matter in rain varies with the amount of rainfall. At the beginning of a storm the amount of wind- borne dust is relatively great and the rain washes this dust from the air resulting in higher concentrations of dissolved salts in the precipi- tation. As the storm continues, the dust is removed from the air and the remaining rainfall is lower in dissolved salts content. The average dissolved mineral content of rainfall for Volusia County is probably no more than 25 mg/1 (milligrams per liter). This value is deduced from the dissolved solids content of several small lakes which have small, closed drainage basins and whose source of water is rainfall and seepage from the relatively insoluble surficial deposits within the basin. Additionally the average dissolved mineral content of rainfall at Ocala, in inland central Florida, and at various sites along the west coast of central Florida is generally no more than 25 mg/1. Rainfall is slightly acid because of the solution of atmospheric CO2 (carbon dioxide) in water droplets, resulting in the formation of H2 CO3 (carbonic acid). Also, industrial operations may add gases to the atmosphere which can produce acids when dissolved in water. The median pH value of the rainfall in Volusia County is about 6. WATER RESOURCES The quality and quantity of water in lakes, streams, and aquifers dictates the usefulness of the water from that particular source. Water changes in chemical quality while moving through the several environments that constitute the hydrologic cycle. Many of these changes are significant and studies of them add to the under- standing of the hydrologic system and permit a more comprehensive Table 3. Selected chemical characteristics of surface waters in Volusia County. Color Dissolved Solids Total Hardness Chloride Sulfate pH Station Name Data (units) (mg/I) (as mg/1 CaCOs) (mg/l) (mg/1) (units) (fig. 1) Max Min Max Min Max Min Max Min Max Min Max Min Middle Haw Creek 1 360 180 35 22 12 6 21 8.0 4.0 0.0 5.4 4.4 Little Haw Creek 2 450 170 39 29 22 10 19 9.0 6.4 .0 6.2 5.1 Tomoka River 4 400 120 197 77 138 47 36 18 13 5.0 7.7 6.4 Deep Creek 5 800 30 790 43 307 18 305 12 9.2 .0 7.5 5.3 (Barberville) Spruce Creek 6 400 40 437 55 310 42 74 20 9.6 4.0 8.5 6.0 St.Johns River 7 270 30 1,090 120 313 44 505 52 153 11 7.5 6.6 Deep Creek (Osteen) 10 260 75 88 28 50 11 21 6.5 21 3.6 7.3 6.2 Lake Winnemissett 29 5 0 129 120 71 63 24 18 61 56 6.5 6.4 Lake Dupont 30 5 0 24 24 9 6 9.5 9.5 4.8 4.0 5.7 5.7 0 co lI N'1 ! S.0 2 0 0 BUREAU OF GEOLOGY atmospheric fallout accumulates on the ground between periods of rainfall. The amount of accumulation depends partly on the length of the period between rainfalls. Thus, longer periods between rain- falls allow greater amounts of mineral matter to accumulate. Hence, the overland flow after periods of infrequent rainfall usually contains greater amounts of dissolved mineral matter than flow during periods of more frequent rain. The amount of dissolved mineral matter in overland flow also depends upon the duration of the storm. Initially, storm runoff contains relatively large amounts of dissolved mineral matter because the rain "washes" the surface of the ground and removes much of the soluble mineral dusts. However, as the storm continues the amount of readily soluble mineral dust decreases so that the overland flow contains less dissolved mineral matter. Variations in chemical quality for a stream whose source is direct rainfall, overland flow and seepage from the shallow ground water is exemplified by Deep Creek in southern Volusia County. Data collected on this stream at a station near Osteen exhibits the rainfall-discharge-mineral content relationship described. Figure 12 shows hydrographs of daily rainfall, discharge, specific conductance (a measure of the ability of water to conduct an electric current, which is a function of the amount and type of ions in the water and thus can be used to estimate the dissolved solids content of the water) and temperature of streamflow for Deep Creek. During prolonged rainy periods following long dry periods (start of the rainy season in June 1965), discharge increases in response to rainfall while specific conductance increases initially with increased discharge but decreases with continued rise in discharge. The hydrograph also shows that the specific conductance is generally lower during periods of frequent rainfall (July 5 to August 20) and higher during periods of drought (May 1-25). The dissolved solids duration curve in figure 13 shows that although there is some variation in values for Deep Creek, the minimum and maximum values are relatively low. The minimum dissolved solids content observed during the 2-year period of record is 28 mg/l while the maximum content is only 135 mg/1. The flat curve suggests that most of the water comes from a single source and the chemical quality shows that the water comes from the clastic aquifer which is composed of slightly soluble materials. Very little seepage from the Floridan aquifer reaches the creek, as indicated by the relatively low dissolved solids content. 40 30 I z ~ I- w 0 ao 0 |50 d 5 3 150 8 10 O0 (. a Iz I 0 3 o 3 -J JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC 1965 AA A ^^ A^~ AV /VA^ V^ "~X 150 100 w a. 80 S60 40 -j 0 30 o 20 I0 -I -I- 1 I I I I II1 I I I 0.050.1 0.2 0.5 2 5 Record used: October 1964 to September 1966 (721 days) , , ,,i 50 60 70 80 90 95 98 99 10 20 30 40 PERCENT OF TIME DISSOLVED SOLIDS EQUALED OR EXCEEDED, VALUE INDICATED I I I I I I I I I I I I I REPORT OF INVESTIGATION NO. 57 Stream temperature is closely related to air temperature and subject to seasonal variation. Stream temperatures may rise or fall after precipitation depending upon the relative temperatures of the streams and of the precipitation; during the warm seasons stream temperatures usually decrease after a rainfall because of the cooling effect of the rain. This relationship is shown on figure 12. The average temperature for Deep Creek during this study was 23C (73 'F). Color and acidity increase after rainfall because rain flushes highly colored and acidic organic materials from the surface. Color is highest during the warm seasons and lowest during the spring drought period. Three analyses of water from Deep Creek having low, medium, and high concentrations of dissolved solids are shown in milliequivalents per liter in figure 14. In an analysis expressed in milliequivalents per liter, unit concentrations of all ions are chemically equivalent. Figure 14 shows that the relative proportions of the constituents remain the same in each of the analyses and that the only major change in chemical quality is in the total amount of dissolved mineral matter. The quality of the water in streams that intercept significant seepage from the Floridan aquifer reflects the influence of the lime- stone of that aquifer and, in some cases, the influence of saline water discharged from the deeper part of the aquifer. The St. Johns River apparently receives discharge from the part of the Floridan aquifer which contains salt water. This discharge results in high concentra- tion of dissolved solids in the river except during periods of high flow. The average dissolved solids content for the St. Johns River near DeLand is about 700 mg/1 and ranges from 120 mg/1 to 1,090 mg/1. The water is highly colored and ranges from slightly acidic to slightly basic. Middle Haw and Little Haw Creeks exhibit chemical characteristics similar to that of Deep Creek near Osteen. These streams are slightly mineralized, highly colored, and slightly acidic. During low flows Deep Creek near Barberville, and to some extent Spruce Creek, exhibit chemical characteristics similar to the St. Johns River. These streams are moderately mineralized, slightly colored, and range from slightly acidic to slightly basic. BUREAU OF GEOLOGY July I- 10, 1966 30 1.5 1.4 1.3 1.2 1.1 90 .9 Feb. 11-20, 1966 Figure 14. Chemical analyses of selected composites of samples from Deep Creek near Osteen showing relative proportions of major mineral constituents. Dec. 1-10, 1965 REPORT OF INVESTIGATION NO. 57 GROUND WATER A description of the aquifers and their hydraulic characteristics has been presented by Wyrick (1960). During the present investiga- tion of the aquifer systems emphasis was on the determination of the rate and quantity of vertical movement of water (recharge) from the clastic aquifer to the Floridan aquifer. The hydrogeologic units as described previously are differen- tiated on the basis of their composition and their prime function in the hydrologic system. The poorly consolidated sediments of the plastic aquifer (Wyrick's nonartesian aquifer) functions primarily as a subsurface reservoir that stores water until some of it leaks into the Floridan aquifer (Wyrick's artesian aquifer). The limestones and dolomites underlying the clastic aquifer constitute a much larger reservoir as the thickness of the Floridan aquifer is greater than 600 feet compared to about 75 feet for the clastic aquifer. The Floridan aquifer readily transmits water and is a major water supply source (Wyrick, 1960, p. 25). CLASTIC AQUIFER The clastic aquifer is composed of poorly consolidated sand, shell and clay. The clay in some areas functions as an aquitard (a less pervious formation) in separating the sand from the shell and in other areas in separating the clastics from the limestone (fig. 4). The sand is predominantly fine grained and has a porosity of about 35 percent. It has a coefficient of storage, based on the coefficient of storage of similar material, of about 0.25 or approximately equal to the specific yield. The shell beds, which have a sand matrix contain large quantities of water but they are seldom utilized for a water supply because sand free water can be obtained only if a well screen is employed. In the vicinity of Oak Hill where the Floridan aquifer water is not potable -because it contains 400-2400 mg/1 chloride, potable water is obtained from shell beds for domestic use. The present (1969) use of water from the clastic aquifer is small compared to the amount of water it has in storage. From an average storage coefficient and saturated thickness, the aquifer is estimated to contain 3 x 1012 gallons of fresh water. To this large volume of water, it is estimated that an average of 400 million gallons are added daily from rainfall for subsequent recharge to the Floridan aquifer. The clastic aquifer will continue to function primarily as a storage reservoir for recharge to the Florida aquifer until techniques of BUREAU OF GEOLOGY well-screen installation and well development in fine sand and shell beds come into common usage locally. Fluctuations of the water table in the clastic aquifer were recorded in several shallow wells. The hydrographs of three of these wells open in the sand show a maximum fluctuation of 5 to 5.5 feet (fig. 6). The water table responds to rainfall and the closer the water table is to the land surface the more responsive it is to rainfall. This is shown by the degree of unevenness of the clastic aquifer hydrographs in figure 6. At site 14, where the water table fluctuates between 1 and 6 feet below the land surface, the hydrograph is most uneven, whereas at site 25, where the water table is between 12 and 17 feet below the land surface, the hydrograph is the smoothest. Water in the clastic aquifer is less mineralized than that in the Floridan aquifer (table 4) because of the lower solubility of the sand. The mineral content of water from shallow wells in the sand ranges from 25 to 50 mg/1 and is higher in the shell beds due to the higher solubility of the shells. The principal dissolved mineral constituents in water from the clastic aquifer are sodium, chloride, calcium and bicarbonate. FLORIDAN AQUIFER The hydraulic characteristics of the Floridan (artesian) aquifer, as reported by Wyrick (1960) are coefficients of transmissibilityl that range from 28,000 to 370,000 gallons per day per foot and a storage coefficient2 of about 0.0007. Water level measurements made during the present investigation were used to construct a map showing the configuration of the aquifer's piezometric surface in November 1966, figure 15.The 1966 map is in general similar to the 1955 piezometric map (Wyrick, 1960, fig. 13) but there are some significant differences. The greatest difference is the portrayal on the 1966 map of a large piezometric low which is less than 10 feet above mean sea level and extends northeast from Blue Springs to DeLand. This piezometric low is a cone of depression that is caused in part by the discharge of Blue Springs. The cone of depression is elongate to the northeast of the spring. The elongation is caused by a preferred direction of permeability (fig. 15), probably a result of faulting. Additional asymmetry resulted when the natural cone coalesced with the cone of depression of DeLand's municipal wells. 1 The rate of flow of water (in common U. S. Geological Survey units) in gallons per day, at prevailing temperature, through a vertical strip of aquifer one foot wide and having a height equal to the thickness of the aquifer, under a unit hydraulic gradient. 2 The volume of water released from or taken into storage per unit volume of aquifer per unit change in head. Table 4. Comparison of ground water quality at various depths in Volusia County. Chemical analyses in milligrams per liter Dissolved Hardness Solids as CaCO3 W o wi s | 00 I Well "0--. "8 ; z ao a Number2 O iz 0 ZU C | 16 290534N- 19 4-21-66 1.3 0.03 6.2 1.3 6.2 0.0 24 0.0 11 0.0 0.1 28 21 2 88 6.7 5 0811750.3 16 290534N- 114 4-21-66 13 .33 63 2.8 7.2 1.3 214 .0 10 .1 .0 202 169 0 370 7.6 5 0811750.1 16 290534N- 260 4-21-66 12 .25 66 9.1 6.6 .4 242 .0 10 .0 .1 223 202 4 360 7.8 5 0811750.2 17 290432N- 7 6-13-66 6.5 .39 6.1 1.9 6.8 .7 5 2.4 20 .2 48 23 19 76 5.2 140 0811449.4 17 290432N- 84 4-18-66 13 2.08 78 1.9 9.1 .7 244 3.6 10 .1 .1 237 203 3 405 7.8 5 0811449.1 17 290432N- 310 4-21-66 15 .90 75 5.6 14 1.6 266 4.4 17 .2 .0 264 210 0 480 7.9 15 0811449.2 1 Number refers to site location on figure 1. 2 Well number refers to latitude and longitude (290534N0811750.3 = lat. 29 '05'34" north, long. 81'1 7'50", well no. 3). BUREAU OF GEOLOGY *____a-to, EXPLANATION COLUTiy -40- PIEZOMETRIC CONTOUR Shaws altitude of the piezometric surface of the Floridan aquifer, November 1966. Contour interval: 5 Feet Datum: Mean Sea Level JOINT OR PROBABLE 0 I 2 3 4 5 MILES Figure 15. Volusia County showing contours on the the Floridan aquifer. piezometric surface of 34 ZA. w3 <&Jo, -ja Ia REPORT OF INVESTIGATION NO. 57 Rainfall in Volusia County was slightly above normal in 1966. Thus water levels, except where influenced by increased pumpage, were a little higher in 1966 than they were in 1955, although the trend for the last 20 years shows a slight decline (1-2 feet) of water level, as represented by the hydrograph of the Barberville well in figure 16. Along the east coast, where pumpage is increasing, water levels have declined about 6 feet as shown by a 10-year hydrograph of a well near Daytona Beach well field (fig. 16). The apparent reduction in the size of the area enclosed by the 40-foot contour between 1955 and 1966 and its slight shift to the west is a result of more data being available for the 1966 map. Another significant feature of the new map (fig. 15) is the piezo- metric low around the New Smyrna Beach well field. This low has probably developed since 1955 as a result of increased pumpage. The volume of fresh water in the Floridan aquifer in Volusia County is estimated at 16 x 1012 gallons. Not all of this water is available for use and only 400 million gallons of the total in the aquifer are estimated to be exchanged daily under present hydrologic conditions. Chemical data were collected at sites consisting of groups of three wells. Each group of wells tap the water table in the clastic aquifer, the upper part of the Floridan aquifer, and a lower part of the Floridan aquifer. Water levels at these selected sites were succes- sively lower with increasing well depth, suggesting a downward move- ment of water. Table 4 gives water quality at various depths from near the surface to well within the limestone of the Floridan aquifer. As water moves through the subsurface it undergoes changes in chemical quality. Rain water which enters the ground begins to dissolve mineral matter and gases from the soil. The amount of mineral matter dissolved depends on the chemical composition of the soil and on the chemical nature of the water. Gases dissolved from the soil include relatively large amounts of carbon dioxide, which in turn produces carbonic acid, an agent that greatly increases the ability of water to dissolve some types of minerals, particularly carbonate minerals. The soil of the county consists primarily of quartz sand with lesser amounts of clay and shells. The sand and clay contribute small amounts of silica (SiO2) to the water and bring about only minor changes in chemical quality; however, the shell beds add significant amounts of calcium and bicarbonate to the water. As the water moves down into the limestone, which underlies the clastic deposits, 14 SU 15 2 s < 16 w is S. W 15 qg 5w 21 3 22 . ~ BARBERVILLE 46 -""21 43 4 c! DAYTONA BEACH 14 > 130 'lo -9 -i 7 1950 1955 1960 1965 ------------------------------------------ 1951701 REPORT OF INVESTIGATION NO. 57 still more calcium and bicarbonate are added to the water. By the process of solution the ground water becomes a calcium bicarbonate type water. Increases in mineral content relate to direction of water flow, allowing greater opportunity for dissolution of the aquifer minerals in the down gradient direction. Chemical quality factors which reflect the solution process can be plotted really and their distribu- tion may be used to show relative direction of water movement in the aquifer. Chloride content of ground water is an important quality factor in Volusia County. Rainwater, which is low in chloride, recharges the ground-water system and displaces the high chloride water that lies at depth in the aquifer. The zone of diffusion between the fresh and saline water moves up and down in relation to the head of fresh water above the zone. This movement causes variations in the quality of water withdrawn from wells that penetrate the zone of diffusion. The chemical quality of water in the upper part of the Floridan aquifer is of particular importance because most of the water used in the county is withdrawn from this zone. Some of the more impor- tant factors that affect ground-water usability in Volusia County are total dissolved solids, total hardness, and chloride content. The total dissolved solids content of water in the upper part of the Floridan aquifer is shown in figure 17. The dissolved solids values range from less than 100 mg/1 to several thousand mg/l and represent water ranging from a calcium bicarbonate type to waters of a sodium chloride type. Water containing low dissolved solids is found in the central part of the county and is principally calcium bicarbonate type water. Here, the low dissolved solids values are probably due to recharge from the ridges and terraces in the central part of the county. Higher dissolved solids values occur along the St. Johns River and along the Atlantic coast, where principally sodium chloride type waters are discharged from the lower parts of the aquifer. Total hardness of water from the upper part of the Floridan aquifer in Volusia County is shown in figure 18. The distribution of the total hardness values is similar to that of the dissolved solids. In the interior of the county this similarity occurs because the solution of limestone accounts for nearly all of the dissolved mineral matter in the water as well as for the property of hardness. The water discharged along the coast and the St. Johns River is higher in both hardness and sodium chloride and this accounts for the increased dissolved solids in these areas. BUREAU OF GEOLOGY U. ~9o 4 Jo, 10.o ots~ 1g. oIv DISSOLVED SOLIDS IN MILLIGRAMS PER LITER C3 0-250 E 250-500 3 500-1000 0 MORE THAN 1000 WELL - FAULT - -- JOINT OR PROBABLE F 0 I 2 3 4 5 MILES Figure 17. Total dissolved solids in ground water Floridan aquifer in Volusia County. from upper part of 38 JA 4.j -- '___________ REPORT OF INVESTIGATION NO. 57 Jo-*o, EXPLANATION TOTAL HARDNESS IN MILLIGRAMS PER LITER 0 0-125 E 125-250 (3 250-325 [f GREATER THAN 325 WELL aeo ---- FAULT S- -- JOINT OR PROBABLE FAU Figure 18. Total hardness of ground water from upper part of Floridan aquifer in Volusia County. .eo BUREAU OF GEOLOGY Chloride content of water from the upper part of the Floridan aquifer in the county is shown in figure 19. Chloride in the county's ground water is derived from rainfall and from the saline water that is present at depth in the aquifer. In areas of recharge the chloride is derived from rainfall and concentrations are generally less than 25 mg/l. In areas of discharge, along the St. Johns River valley and the Atlantic coast, saline water permeates the entire thickness of the aquifer and chloride concentrations may reach several thousand milligrams per liter. The dissolved solids, hardness, and chloride maps show similar east-west indentations of more highly mineralized water (figs. 17, 18, 19). The indentations, or reentrants are parallel to either faults or joint systems. Highly mineralized water from deep in the aquifer may move into the upper part of the aquifer along fault planes or joint systems. The reentrant at Ponce de Leon Springs is aligned with the reentrant at Spruce Creek along the east coast; both are probably situated along a fault. Another reentrant extends into the DeLand ridge between DeLand and Orange City. Wyrick (1960) estimated the depth to saline water (greater than 1,000 mg/1 of chloride) in the aquifer in the center of the county to be about 750 feet. From a deep well drilled in 1969, data were obtained which showed that the depth to saline water is 1450 feet. This apparent change in depth is a result of new data rather than an actual change in the depth to saline water. The saline-fresh water zone of diffusion can shift up and down though, as a result of changes in the hydraulic heads in the upper and lower parts of the aquifer. This movement produces changes in the ground-water quality for parts of the aquifer near this zone. For example, lowering the hydraulic head in the upper part of the aquifer could result in upward movement of water from the lower part of the aquifer. This movement may in turn result in increased salt content of wells located near the zone of diffusion. This process is generally called salt-water encroachment and is described in detail by Wyrick (1960, p. 41-48). The chloride content of ground water in the upper part of the Floridan aquifer was measured during the mid 1950's and again in the mid 1960's. A comparison of these two periods shows that during the drought conditions of the mid 1950's, the chloride content of the ground water was higher than during the relatively wet conditions of the mid 1960's. The most probable source for the higher chlorides was from recharge water which contained a higher chloride content. The volume of soluble airborne chloride salts is REPORT OF INVESTIGATION NO. 57 -9 ^o , / EX PLAN AT ION CHLORIDE CONTENT IN MILLIGRAMS PER LITER M 0-25 E] 25- 250 250-1000 f~J MORE THAN 1000 WELL - FAULT - JOINT OR PROBABLE F 0 I 2 3 4 5 MILES Figure 19. Chloride content of ground water from upper part of Floridan aquifer in Volusia County. ego eo, "'90, 3o. b /0' 9000 J Oo, m Table 5,. Chemical analyses of springs In Volusia County, Chemical analyses in milligrams per liter Ponce de Leon Springs near DeLand, Fla. (site 31, fig. 1) 10-21-64 6.9 0.01 48 18 135 5.6 128 86 240 0.1 5.0 558 195 90 1,000 7.7 1 I 5-. 867 7.0 .01 S9 6.81 3 2.0 122 10 60 .2 2.6 242 221 126 26 415 7.7 0 29.5 Blue Springs near Orange City, Fla. (site 32, fig. 1) 5-26-66 8.8 0.00 70 36 301 10 149 78 550 0.1 0.6 1,130 322 200 2,120 7.2 0 156 5- 9-67 8.6 .00 57 26 215 7.7 160 52 388 .2 .8 876 835 250 119 1,520 7.6 0 155 Green Springs near Osteen, Fla. (site 33, fig. 1) 2-12-65 740 - 2,500 -I REPORT OF INVESTIGATION NO. 57 probably constant during wet and dry periods, but during wet periods the chloride concentration in precipitation and surface water is less due to the dilution effect. SPRINGS Springs along the flanks of the DeLand ridge discharge water which has infiltrated the ridge (fig. 15). Blue Springs, the ninth largest spring in Florida (U. S. Geological Survey, 1964, p. 508), is a first magnitude spring with an average flow of 105 mgd. Another large spring is Ponce de Leon Springs which has an average flow of 20 mgd. Both springs are on the western edge of the DeLand ridge. Green Springs, a relatively small spring, discharges water from the south end of DeLand ridge at an average flow of 0.5 mgd. The flow from just these three springs is almost 10 times the amount of water presently withdrawn for public supplies in the county, but high chlorides in their water (table 5) make it undesirable for public supply. Ponce de Leon Springs exhibits an unusual relationship between the discharge and dissolved mineral content of its waters. The dissolved mineral content of most springs decreases with increasing discharge; but for Ponce de Leon Springs, the chloride content, which is a major mineral constituent, increases with increasing discharge, figure 20. The scatter of the points is probably due to the variable control on the head of the spring. The outlet structure (control), which forms the spring into a swimming pool, is manipu- lated frequently to adjust the water level. During periods of low water levels, when the chloride concentrations increase in the surface and ground waters, chloride concentration in Ponce de Leon Springs reach lows of 60 mg/l, which is well below the maximum limit of 250 mg/1 recommended by the U. S. Public Health Service (1962). The phenomenon of high discharge and high chloride concentra- tion is not fully understood but one explanation is that during periods of greater recharge the increased fresh-water head causes the zone of diffusion to be suppressed under the DeLand ridge. As the zone of diffusion is suppressed, fresh water displaces the water with greater chlorides in the zone of diffusion, which is then discharged through the springs. WATER AVAILABILITY AND USE The availability of water in Volusia County depends on how and where water is removed from the hydrologic system. The BUREAU OF GEOLOGY 0) M _______________ ______________ __________________ 10) W < Cd 0 U) z 0 -J1 -J (.9 z 0 -J Ld (9 Ir _M C. _____I 1 a 0 0 o 0 311i1 83d SI/V1I91771N 3110-7HO Ito Figure 20. Relation of chloride concentration to discharge at Ponce de Leon Springs. hydrogeologic conditions in the central part of the county are such that the aquifer is full and rejecting recharge. If the piezometric surface were lowered in this area by withdrawing water from the Floridan aquifer for use, recharge would increase from capture of water from evapotranspiration and runoff. The increase in recharge would increase the amount of water available. REPORT OF INVESTIGATION NO. 57 In Volusia County the difference between precipitation and evapotranspiration depends on the hydrogeologic conditions and is in the form of runoff and/or ground-water discharge. If average condi- tions for the whole county are used, an estimate of this difference can be made. Average annual rainfall over the county is 52 inches (3,000 mgd) and average evapotranspiration is estimated at 35 inches (2,000 mgd) based on values used by other investigators for similar areas. Kohler and others (1959, pl. 2) estimated the average annual lake evaporation in this part of central Florida to be about 46 inches. Evapotranspiration from the Green Swamp area in central Florida was estimated by Pride and others (1966, table 18) to be about 37 inches. In Orange County, Lichtler and others (1968, p. 145) estimated that evapotranspiration is 70 percent (36 inches) of rainfall. In Volusia County the difference of 17 inches between precipitation and evapotranspiration is accounted for by surface runoff and ground-water drainage. The average annual surface runoff as determined in this investigation is 10 inches (590 mgd) which leaves 7 inches (410 mgd) as an estimation of ground-water dis- charge. The amount of water used presently from the ground-water system is about 26 mgd or just less than 0.5 inch of water over the entire county. Most large production wells are used for public water supplies and as such are drilled relatively near the centers of population along the Atlantic Coast and St. Johns River. Because the depth to saline water is shallower in these areas than in the central part of the county, wells are generally not over 300 feet deep. These large diameter public supply wells (8-12 inch) will generally yield 1,000 to 1,500 gallons per minute. As well fields are developed nearer the central part of the county, well yields should increase somewhat due to the greater thickness of fresh-water-saturated aquifer there. An estimate of the amount of readily available water through- out the whole county is 300 mgd. This 300 mgd (equal to 5 inches of water over the county) would be available from a slight decrease in evapotranspiration, a result of lowering the water table; a slight decrease in runoff, a result of greater infiltration; and a slight decrease in natural ground-water discharge, a result of a lower gradi- ent on the piezometric surface. Under the hydrogeologic conditions in Volusia County, one way of increasing the amount of available water is to use it. The major uses of water are for public supply, rural supply, irrigation, and industry. Water for recreation is also a major use but is not so considered herein. In this report water is considered used when it is removed from an aquifer or surface-water body. BUREAU OF GEOLOGY 20 1950 1960 1970 Figure 21. Graph of water use in Volusia County, 1950-1970. Of the 25.91 mgd used in Volusia County in 1967, 15.8 mgd or 60 percent Was used for public supply. Water use from 1950 to 1967 and extrapolated to 1970 is shown in figure 21. In the 20-year inter- val the amount of water used for public supply will more than double, the amount of water for irrigation will increase more than four times whereas water for rural and industrial uses will increase but slightly. 1 Does not include cooling water used in electrical generating. REPORT OF INVESTIGATION NO. 57 Ninety-five percent of the water used in Volusia County comes from ground water and all but a fraction of a percent of this comes from the Floridan aquifer. In 1967, 24.5 mgd was withdrawn from the Floridan aquifer, all of which was recharged by rainfall on Volusia County. The amount of water used for cooling in generating electricity has not been included in the water use figures but is shown in table 5. It is withdrawn from the Atlantic Ocean and the St. Johns River to cool the generating plants and then returned to the same sources. Water is not uniformly available throughout the county. More water is available in the central part of the county where the runoff is greatest and the fresh-water part of the aquifer is thickest. The water quality maps (figs. 17, 18, 19) show that fresh water is unavail- able from the Floridan aquifer along the Atlantic Coast and St. Johns River. Water data for the public supplies, rural supply, irrigation and industry are given in table 6. To diminish the possibility of salt-water encroachment from the ocean that is induced by increased pumpage, Daytona Beach, the largest water user in the county is constructing new well fields to the west of the city and abandoning well fields nearer the ocean. The location of the major well fields in the county are shown on figure 22. Chemical analyses of public water supplies are given in table 7. SUMMARY Most of the fresh water in Volusia County comes from the average yearly 52 inches of rain that falls on the county. The natural topography helps retain much of this water within the county. Karst and shoreline ridges with their high rates of infiltration allow little or no runoff. Although marine terraces have the highest runoff, their streams do not have deeply incised channels and the water table remains near the surface. Low sand ridges at the escarpment of each terrace prevent streams from flowing directly to the ocean. The two major hydrogeologic units are the clastic aquifer and the underlying Floridan aquifer. The clastic aquifer is important as a reservoir in which local rainfall is stored until it moves downward to recharge the Floridan aquifer or is lost to evapotranspiration and streamflow. The clastic aquifer comprised of sand, clay and shell has a porosity of about 35 percent and a coefficient of storage of about 0.25. The infiltration capacity of the surficial sand is large, and it absorbs much of the rainfall except in areas where the water table is ,PUMPAGE MGD (million gallons per day) City Served Ownership Source of Well Wellh wells variation Yearly Average (1967) Supply Fields (feet) (1967) Breaeewood Park1 Daytona Beach DeBarry DeLand DeLand Deltona Edgewater Holly Hill Lake Beresford Water Assoc. 250 60,000 Private Floridan aquifer Municipal Floridan aquifer Private Floridan aquifer Municipal Floridan aquifer Private Floridan aquifer Private Floridan aquifer Municipal Floridan aquifer Municipal Floridan aquifer Private Floridan aquifer 1 26 1 6 2 8 2 5 2 0.01..04 4.3*9.6 .03-.1 1.2-4.2 .2-4 300-350 250 225 200 1967 0.02 1933 1.4 1954 4.7 1963 6,0 1950 3.5 1955 4.7 1964 5.7 1951 3.7 1956 4.8 1965 6.3 1952 4.1 1958 5.5 1966 6.0 1953 4.0 1962 5.9 1967 7.0 1966 .05 1967 .06 1963 2.1 1964 2.0 1965 2.0 1966 1.8 1967 1.9 1967 .2 1966 .6 1967 1.0 1963 .15 1964 .20 1965 .20 1966 .23 1967 .30 1954 .46 1959 .47 1964 .64 1955 .37 1960 .46 1965 .68 1956 .45 1961 .52 1966 .69 1957 .57 1962 .62 1967 .72 1958 .51 1963 .72 1965 .02 1966 .02 1967 .03 650 18,800 2,200 3,700 3,700 11,500 360 15-1.2 .02-.04 Table 6, Water uW In Volunla County, PUBLIC SUPPLY Orange City " Lake Helen New Smyrna Beach Ormond Beach Port Orange 3,250 1,500 16,500 24,000 6,000 Private Municipal Municipal Municipal Floridan aquifer Floridan aquifer Floridan aquifer Floridan aquifer Municipal Floridan aquifer RURAL SUPPLY 2 WATER USE (MGD) Year Population Ground Water Surface Water 1956 30,000 1.8 0.2 1965 32,000 2.1 .2 1967 25,000 2.0 .2 1 Unincorporated. 2 Includes all people using private domestic wells or obtaining water from small systems supplying less than 100 people. 3 Water used in electrical generating. 460 200 200-220 2 5 .04-.12 1.2-4.0 1.4-2.8 .38-.85 1960 1961 1962 1963 1964 1963 1964 1967 1963 1964 1965 1966 1967 1952 1953 1954 1955 1956 1953 1954 1955 1956 1957 .19 1965 .15 .23 1966 .23 .25 1967 .23 .21 .17 .06 .07 .07 1.5 1.7 1.7 1.8 2.0 .64 1957 1.0 1965 .68 1958 1.5 1966 .72 1962 1.5 1967 .83 1963 1.7 .95 1964 1.5 .15 1958 .27 1963 .19 1959 .29 1964 .21 1960 .29 1965 .21 1961 .31 1966 .23 1962 .32 1967 0 0 8 0 0 1V z z 0. ".4U IRRIGATION I WATER USE (MGD) ACRES Year Ground Water Surface Water Citrus Truck Fern Other 1965 5.5 1.1 1,500 500 1,400 300 1967 6.1 1.1 1,500 500 1,600 300 INDUSTRIAL GROUND WATER (MGD) SURFACE WATER3 (MGD) Year Fresh Saline Fresh Saline 1965 0.4 0.2 144 1967 .5 .2 144 16 REPORT OF INVESTIGATION NO. 57 at the surface. The shell beds contain a relatively large amount of water and in places along the coast are a source for domestic water supplies. Dissolved solids concentration of the water in the clastic aquifer is lowest in the sand beds and higher in the shell beds. The Floridan aquifer, comprised of limestone and dolomitic limestone, underlies all of Volusia C6unty. It is a semiconfined artesian aquifer and the principal source of water supply in the county. A hard, dense, dolomitic zone divides the aquifer into an upper and lower part. Geologic structure appears to be a major factor in the hydrogeologic system of the Floridan aquifer. Faults form a fault-block that encloses the piezometric high in the center of the county. Zones of highly mineralized water occur along fault planes or joint systems. Water levels in the upper part of the aquifer along the coast have declined about 5 feet since 1955. This is attributed to increased pumping for the rapidly growing east coast area. Other areas, where pumping has not greatly increased, exhibit stable levels. Water in the upper part of the Floridan aquifer is of good chemical quality in most of the interior of the county. It is principally calcium bicarbonate type water but there is also some sodium chloride type water in this area. Aquifer chlorides as low as 10 mg/1 and hardness of 100 mg/1 are found in the interior. However, highly saline water is found at depth in the aquifer and in the discharge areas along the coast and the St. Johns Valley. Recharge to the Floridan aquifer occurs throughout much of Volusia County. Some recharge generally occurs wherever the water table is higher than the piezometric surface. However, areas of piezometric highs should not be considered principal recharge areas in Volusia County. Such a high occurs in the -western part of the Talbot terrace where the piezometric surface is near or above the water table most of the time, a condition which prevents recharge to the Floridan aquifer. Areas where the water table is higher than the piezometric surface such as parts of the karst ridge and the eastern part of the Talbot terrace are areas of greater recharge. Most of the lakes in Volusia County are on the DeLand ridge, where there are about 120 larger than 5 acres. These lakes, with a few exceptions, are generally shallow (less than 20 feet) and have a small seasonal fluctuation (less than 3 feet). Lakes which are surrounded by agricultural or residential land are more highly mineralized than lakes isolated from human activity. Streamflow from the county averages about 590 mgd. This is over 20 times the daily water use, however, the minimum flow during the spring dry season is less than 5 mgd. Volusia County 52 BUREAU OF GEOLOGY streams have very little channel storage and the potential of using streams for a water supply is slight due to their flow characteristics. Most of the streams are slightly mineralized, highly colored and slightly acid. The flow of the St. Johns River is about 80 times greater than the amount of water used daily in the county. However, the water is of poor chemical quality and generally unsuitable for most uses. At times, during low flow, some streams are affected by discharge from the Floridan aquifer and exhibit chemical quality similar to the ground water. It is estimated that 300 mgd on an average throughout the county is readily available for use. This water could be obtained by lowering the piezometric surface through pumping in the central part of the county which would decrease evaporation, runoff, and natural ground-water discharge and increase infiltration. Total water use in Volusia County in 1967 was 26 mgd, of which 95 percent was derived from the Floridan aquifer. Table 7. Chemical analyses of public water supplies.1 Chemical analyses, in milligrams per liter Cal- Magne- Potas- Bicar- Fluo- Ni- Silica Iron cium sium Sodium sium bonate Sulfate Chloride ride trate Dissolved Total City Date (SiO2) (Fe) (Ca) (Mg) (Na) (K) (HCOg) (S04) (Cl) (F) (NOS) Solids Hardness pH Daytona Beach 19572 21 14 104 5 253 353 0 32 315 280 19652 .2 101 9 276 46 286 7.2 DeLand 19234 16 .07 39 6.8 7.53 140 9.0 12 4.3 164 125 (Municipal) 19624 8.2 .01 46 6.6 9.5 1.8 156 12 16 0.2 .0 177 142 8.0 DeLand 19654 7.3 .00 39 6.0 6.7 .8 136 13 11 .2 .0 151 122 7.7 '(Private) Deltona 19654 .1 50 5 128 5 28 .5 238 146 7.4 Holly Hill 1952 94 18 333 347 4 67 484 310 1966 23 .02 101 12 356 5 74 .4 1 508 308 7.2 Lake Beresford 1965 10 .06 39 4 12 .9 110 15 24 .1 5 188 114 7.4 Water Assoc. 1967 .03 43 5 122 25 45 215 130 7.4 Orange City 1964 .3 68 8 217 10 242 206 7.0 Lake Helen 1950 0 58 4 195 0 10 .1 210 160 7.4 1958 .02 59 6 180 3 13 .05 203 174 7.5 New Smyrna 1950 1.1 116 8 381 0 60 .2 465 324 7.4 Beach 1961 .15 31 6 331 10 79 .15 488 196 7.9 Ormond Beach 1958 .3 0 104 16 95 342 8 149 675 324 7.3 19624 19 .05 107 21 90 2.2 322 9.6 200 .3 .1 608 354 8.0 1 Untreated water. 2 Airport well field. 3 Includes potassium. 4 Analyses by U. S. Geological Survey. REPORT OF INVESTIGATION NO. 57 Ninety-five percent of the water used in Volusia County comes from ground water and all but a fraction of a percent of this comes from the Floridan aquifer. In 1967, 24.5 mgd was withdrawn from the Floridan aquifer, all of which was recharged by rainfall on Volusia County. The amount of water used for cooling in generating electricity has not been included in the water use figures but is shown in table 5. It is withdrawn from the Atlantic Ocean and the St. Johns River to cool the generating plants and then returned to the same sources. Water is not uniformly available throughout the county. More water is available in the central part of the county where the runoff is greatest and the fresh-water part of the aquifer is thickest. The water quality maps (figs. 17, 18, 19) show that fresh water is unavail- able from the Floridan aquifer along the Atlantic Coast and St. Johns River. Water data for the public supplies, rural supply, irrigation and industry are given in table 6. To diminish the possibility of salt-water encroachment from the ocean that is induced by increased pumpage, Daytona Beach, the largest water user in the county is constructing new well fields to the west of the city and abandoning well fields nearer the ocean. The location of the major well fields in the county are shown on figure 22. Chemical analyses of public water supplies are given in table 7. SUMMARY Most of the fresh water in Volusia County comes from the average yearly 52 inches of rain that falls on the county. The natural topography helps retain much of this water within the county. Karst and shoreline ridges with their high rates of infiltration allow little or no runoff. Although marine terraces have the highest runoff, their streams do not have deeply incised channels and the water table remains near the surface. Low sand ridges at the escarpment of each terrace prevent streams from flowing directly to the ocean. The two major hydrogeologic units are the clastic aquifer and the underlying Floridan aquifer. The clastic aquifer is important as a reservoir in which local rainfall is stored until it moves downward to recharge the Floridan aquifer or is lost to evapotranspiration and streamflow. The clastic aquifer comprised of sand, clay and shell has a porosity of about 35 percent and a coefficient of storage of about 0.25. The infiltration capacity of the surficial sand is large, and it absorbs much of the rainfall except in areas where the water table is REPORT OF INVESTIGATION NO. 57 REFERENCES CITED Barnes, H. H., Jr. 1966 (and Golden, H. G.) Magnitude and frequency of floods in the United States: U. S. Geol. Survey Water-Supply Paper 1674, 409 p. Brown, D. W. 1962 (and Kenner, W. E., and Crooks, J. W., and Foster, J. B.) Water resources of Brevard County, Florida: Fla. Geol. Survey Rept. Inv. 28, 104 p. Florida Development Commission 1965 Population of Florida: Fla. Development Comm., Tallahassee, Florida, 19 p. Knochenmus 1968 Kohler, M. A 1959 Lichtler, W. 1968 Pfischner, F. 1968 Pride, R. W. 1966 Puri, H. S. 1964 ,D. D. Surface drainage characteristics of Volusia County: Fla. Geol. Survey Map Series 30. (and Norderson, T. J., and Baker, D. R.) Evaporation maps for the United States: U. S. Weather Bureau Tech. Paper 37, 13 p. F. (and Anderson, Warren, and Joyner, B. F.) Water resources of Orange County, Florida: Fla. Geol. Survey Rept. Inv. 50, 150 p. L. Relation between land use and chemical characteristics of lakes in southwestern Orange County: U. S. Geological Survey Prof. Paper 600-B, p. B190 B194. (and Meyer, F. W., and Cherry, R. N.) Hydrology of Green Swamp area in central Florida: Fla. Geol. Survey Rept. Inv. 42, 137 p. (and Vernon, R. 0.) Summary of the geology of Florida and a guidebook to the classic exposures: Fla. Geol. Survey Spec. Pub. 5, 312 p. Schneider, Robert 1964 Cenomanian-Turonian aquifer of central Israel Its development and possible use as a storage reservoir: U. S. Geol. Survey Water- Supply Paper 1608-F, 20 p. Snell, L.J. 1970 (and Anderson, Warren) Water resources of Northeast Florida: Fla. Dept. Nat. Res., Bur. Geology Rept. Inv. 54. U. S. Dept. Health, Education and Welfare 1962 Public Health Service drinking water standards: Pub. No. 956, p. 33. U. S. Geological Survey 1964 Surface water records of Florida: Streams, No. 1, p. 508. BUREAU OF GEOLOGY Visher, F. N. 1967 (and Wetterhall, W. S.) Effect of filled cavities on the hydrology of the limestone terrain in Florida: In Abstracts of papers submitted for the meeting in Tallahassee, Florida, March 30-31 and April 1, 1967: Southeastern Sec., Geol. Soc. America. Wyrick, G. G. 1960 The ground-water resources of Volusia County, Florida: Fla. Geol. Survey Rept. Inv. 22, 65 p. REPORT OF INVESTIGATION NO. 57 APPENDIX The following table lists sites where hydrologic data on lakes, streams, aquifers and springs were collected. Data were collected at some sites prior to the investigation and constitute a long record of hydrologic information whereas other sites were established during the investigation. The location, type, frequency and period of record for each site are given in the table. Table 8. Hydrologic data-collection sites in Volusia County and vicinity. Frequency of record: r, Continuous; p, Periodic; d, number of analyses. Daily (10) Total STREAMS Site No. on figure 1 Location Middle Haw Creek at Relay station, near Bunnell Little Haw Creek, at State Hwy. 11, near Bunnell Little Tomoka River near Ormond Beach Tomoka River near Holly Hill Deep Creek near Barberville Spruce Creek near Samsula St. Johns River near DeLand St. Johns River near Sanford Deep Creek diversion canal near Osteen Deep Creek near Osteen Cow Creek near Maytown St. Johns River, above Lake Harney, near Geneva Type and frequency of record Dr A(10) Dp A(12) Dp A(9) Dr A(12) Dp A(13) Dr A(ll1) Dr A(47) Sr, Dp A(13) Sd A(9) Dr Pd A(69) Dp A(8) Sr, Dp A(13) Period of record October 1964 to September 1966 1964-66 1964-66 1964-67 1943, 1945-46, 1956, 1962-67 1964-66 October 1964 to September 1967 1964-67 1964-67 1964-67 May 1951 to September 1967 1964-67 October 1933 to September 1967 1948-49, 1954, 1962, 1966-67 July 1941 to September 1967 1954, 1962, 1965-67 October 1964 to September 1966 1964-66 October 1964 to September 1966 1964-66 1964-66 1964-66 July 1941 to September 1967 1957-58, 1962, 1966-67 Type of record: D, Discharge and stage; A, Standard chemical analysis; S, Stage; P, Partial chemical analysis. BUREAU OF GEOLOGY WELLS Site No. on figure 1 13 14 15 16 17 18 19 20 21 22 23 Location 290842N0810846.11 290655N0811112.1 290655N0811112.2 290655N0811112.3 290541N0811329.1 290534N0811750.1 290534N0811750.2 290534N0811750.3 290432N0811449.1 290432N0811449.2 290432N0811449.3 290432N0811449.4 290251N0810014.1 290142N0811059.1 290138N0812032.1 290138N0812032.2 290106N0811321.1 290106N0811321.2 290106N0811321.3 290107N0810620.1 290107N0810620.2 290107N0810620.3 285904N0811526.1 285904N0811526.2 285904N0811526.3 Depth feet 100 95 304 18 351 114 260 19 84 310 47 7 700 91 62 500 92 340 47 111 21 282 222 22 325 Type and frequency of record Sp A(1) Sr A(1) Sr A(1) Sr. A(1) Sr Sp Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) A(1) Sp A(6) Sp A(1) Sr A(1) Sr Sp A(6) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Period of record 1965-67 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 May 1955 to May 1965 1965-67 April 1966 to December 1967 1966 April 1966 to December 1967 1966 April 1966 to December 1967 1966 January 1966 to August 1967 1966 January 1966 to August 1967 1966 January 1966 to August 1967 1966 - 1966 1965-67 1965-66 1965-67 1966 April 1966 to June 1967 1966 April 1966 to June 1967 1967 1965-66 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 January 1966 to December 1967 1966 1 Well number refers to latitude and longitude (290842N0810846.1 = lat. 29 08'42" north, long. 81 08'46", well no. 1.) .. ., . 285655 285655 285655 REPORT OF INVESTIGATION: N0811656.1 171 Sr A(1) N0811656.2 32 Sr A(1) iN0811656.3 70 Sr 285643N0811226.1 285643N0811226.2 285643N0811226.3 285221N0810950.1 285221N0810950.2 291130N0810417.2 97 37 202 222 92 500 A(i) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sr A(1) Sp Pp N NO. 57 5S January 1966 to August 1967 1966 January 1966 to August 1967 1966 January 1966 to August 1967 1966 April 1966 to December 1967 1966 April 1966 to December 1967 1966 April 1966 to December 1967 1966 April 1966 to June 1967 1966 April 1966 to June 1967 1966 1955-67 1955-67 LAKES Site Type and No. on frequency figure 1 Location of record Period of Record 27 Lake Winona near Sr March 1965 to September 1967 DeLand A(3) 1965-67 28 Lake Hires near Sr March 1965 to September 1966 DeLand A(2) 1965-66 29 Lake Winnemissett near Sr March 1965 to September 1967 DeLand A(4) 1965-67 30 Lake Dupont near Lake Sr March 1965 to September 1966 Helen A(2) 1965-66 SPRINGS 31 Ponce de Leon Springs Dp 1929, 1932, 1946, 1956, 1960 near DeLand 1964-67 A(4) 1923, 1946, 1964, 1967 P (8) 1965-67 32 Blue Springs near Dp 1932-67 Orange City A(3) 1964-67 P(10) 33 Green Springs hear Dp 1932, 1960, 1965, 1966 Osteen P(1) Pp ----------------------------------! ------- 1 - 5 '' IV J) ) c PLJ rN~M ..-COUN'rY LAKE "go GEORG0E / 30 ro / 8 i~~.,,g , 000 rORMOND BEACH DAYTONA BEACH IZ' ~ /0, 500 EXPLNATOANG ALTITDE O LAN SURFACE NENW SMYRNA o ' a BEACH 0 OnO cou h, E 25-50 S50-75 00s seo 75-000 ,I ,' I ,I I I COUNTY ,, ALTITUDE OF LAND SURFACE '~ *F ABOVE 100 0 2 45 MILES 0 7 0 Figure 3. Topographic map of Volusia County. VOLUAGER CO. VOLUSIAFCO. BEACH VOLUSIA CO. BREVARD CO. i 0 5 10 MILES 1 LULJJ - 50' - SEA LEVEL - 50' - 100' - 150 - 200' - 250' - 50' - SEA LEVEL - 50' - 100' -150' - 200' - 250' -- PROBABLE FAULT 5 MILES exaggerated EXPLANATION SAND PLASTIC CLAY AQUIFER --- CLA S50 SHELL - SEA LEVEL -50 FLORIDAN LIMESTONE -1001 AQUIFER DOLOMITIC -5 LIMESTONE - 150' 22 TEST WELL. REFER TO - 200' FIGURE I AND TABLE 8. - 250' SEA LEVEL Figure 4. Fence diagram of hydrogeologic sections in Volusia County. 50 -20 SEA LEVEL - 50' - 150d- 200' - 25d - 0,0 O~25 0 Vertical I 2 scale 3 4 Greatly greatly I |DeLand Talbot metric Ridge Terrace rfoce (FLORIDAN AQUIFER) I St Johns River Block diagram of part of Volusia County showing the movement of water. Al K' 'I MSL FLRD GEOLIOWC( ICA SURflViEWY~ COPYRIGHT NOTICE [year of publication as printed] Florida Geological Survey [source text] The Florida Geological Survey holds all rights to the source text of this electronic resource on behalf of the State of Florida. The Florida Geological Survey shall be considered the copyright holder for the text of this publication. Under the Statutes of the State of Florida (FS 257.05; 257.105, and 377.075), the Florida Geologic Survey (Tallahassee, FL), publisher of the Florida Geologic Survey, as a division of state government, makes its documents public (i.e., published) and extends to the state's official agencies and libraries, including the University of Florida's Smathers Libraries, rights of reproduction. The Florida Geological Survey has made its publications available to the University of Florida, on behalf of the State University System of Florida, for the purpose of digitization and Internet distribution. The Florida Geological Survey reserves all rights to its publications. All uses, excluding those made under "fair use" provisions of U.S. copyright legislation (U.S. Code, Title 17, Section 107), are restricted. Contact the Florida Geological Survey for additional information and permissions. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MILLISECOND | CLASS.METHOD | MESSAGE |
|---|---|---|
| 0 | sobekcm_page_globals.constructor | |
| 0 | sobekcm_page_globals.constructor | Application State validated or built |
| 0 | sobekcm_database.verify_item_lookup_object | |
| 0 | sobekcm_page_globals.constructor | Navigation Object created from URI query string |
| 0 | sobekcm_database.verify_item_lookup_object | |
| 0 | sobekcm_page_globals.display_item | Retrieving item or group information |
| 0 | sobekcm_page_globals.get_entire_collection_hierarchy | Retrieving hierarchy information |
| 0 | sobekcm_assistant.get_entire_collection_hierarchy | |
| 0 | cached_data_manager.retrieve_item_aggregation | |
| 0 | cached_data_manager.retrieve_item_aggregation | Found item aggregation on local cache |
| 0 | item_aggregation_builder.get_item_aggregation | Found 'all' item aggregation in cache |
| 0 | system.web.ui.page.page_load (ufdc.page_load) | |
| 0 | sobekcm_page_globals.constructor.on_page_load | |
| 0 | html_echo_mainwriter.add_style_references | Adding style references to HTML |
| 0 | html_echo_mainwriter.add_text_to_page | Reading the text from the file and echoing back to the output stream |
| 4 | html_echo_mainwriter.add_text_to_page | Finished reading and writing the file |