UNITED STATES DEPARTMENT OF THE INTERIOR
MAP SERIES NO. 72 GEOLOGICAL SURVEY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
published by BUREAU OF GEOLOGY
RIVER BASIN AND HYDROLOGIC UNIT MAP
HYDROLOGIC UNIT CODE
C. S, Conover and S. D. Leach
U. S. GEOLOGICAL SURVEY
in cooperation with the
BUREAU OF GEOLOGY
FLORIDA DEPARTMENT OF NATURAL RESOURCES
This map and accompanying table delineate the "river basins" and the
"Hydrologic Units" in Florida. A river basin consists of a drainage system
composed of a surface stream or a body of surface water together with all
tributary surface streams and bodies of water. A river basin contributes
runoff to a stream and is bounded by a drainage divide.
A Hydrologic Unit is a geographic area designated as a basis for
cataloging and processing the large volumes of hydrologic data and other
information that are accumulating in the National Water Data network.
Retrieval and statistical analysis of the large volumes of hydrologic data in
storage are handled by means of an electronic computer system.
River basins in Florida may encompass many square miles, such as the
Suwannee River basin, or less than a square mile, such as a small basin that
is tributary to a tributary of the Suwannee River basin. Delineating the
drainage divide of a river basin is prerequisite to evaluating the hydrology
of the stream system within that basin. In particular, a determination of the
drainage area of a basin is needed for an estimation of the amocat of runoff
available as water supply, for flood evaluation and forecasting, for design of
various water control and drainage works, and for water management,
regulation, and allocation. The drainage divide is commonly delineated by
using topographic maps which show altitudes of the land surface. On such a
map, a line is drawn along the ridge or drainage divide that separates
adjacent stream valleys. If the line is begun at the mouth of a stream and is
drawn along the drainage divide so as to completely encircle the stream, its
tributaries, and the land drained by the system, the line is the basin
boundary and the land within it is the drainage basin.
In Florida, which for the most part has little topographic relief,
drainage divides are difficult to delineate and even after being delineated,
frequently can be hydrologically misleading. Where the ridge between
basins is indistinct, such as the one between the St. Johns River basin above
the Oklawaha River and the Kissimmee River basin, and is low enough to be
topped by floodwaters, it functions as a basin boundary only part of the
time. During floods, water in one basin thus can move to an adjacent basin
and run off through the stream system of the adjacent basin. Where the
ridges between basins are particularly low, for example south of Lake
Okeechobee, natural drainage divides are somewhat indeterminate.
An area effectively encircled by dikes and levees can be treated as a
basin because the dikes and levees form artificial divides. In a large area
where dikes and canals occur in great profusion, natural divides are not
functional because runoff can be diverted across these divides to another
basin with relative ease. In southern Florida natural basin and subbasin
boundaries may not be permanent because construction of drainage canals
S and dike systems is a continuing process.
Although a basin boundary consisting of a distinct ridge indicates that
surface water does not cross the boundary in either direction to add to or to
subtract from the flow of the stream system, it does not follow that all the
surface-water flow in the system in Florida originates in the basin. The
hydraulic highs of the ground-water system in Florida, a system repre-
sented primarily by the Florida aquifer, do not coincide with the topographic
highs of the surface-drainage system. Accordingly, the flow of most streams
in Florida is not consistently related to the size of the drainage basin. For
example, additions to normal basin flow can come from springs whose source
of water is outside the drainage basin. Conversely, deficiencies in flow result
from natural "non-contributing areas" in a basin and from man-made inter-
i -- '" -.i .. ..-. ..- ,. i .,, 's Prairie in the
.... ,r .,- without surface
outlets that lie within a larger basin. Water from such basins may flow to
adjacent basins by means of the underlying aquifer system.
The area extent of the basins which are fully enclosed-those that
drain to a common point on a stream-are given in square miles under
Drainage Area in the table. The drainage areas listed include the the parts that
are in Alabama or Georgia. The areas of poorly defined interbasin coastal
areas that do not drain to a point, and intervening and partial drainage areas
are given under Hydrologic Units (Accounting and Cataloging) in table 1 and
include only those parts that are in Florida.
The areal extent of drainage basins is determined by using standard
procedures outlined in Bulletin 4 of the Subcommittee on Hydrology,
Federal Inter-Agency River Basin Committee (1951). Drainage areas are
theU. S. .. I,
areas give- I I .
Survey in "Surface Water Records of Florida."
Hydrologic Units depict the basin real planning units and form a
national system for cataloging hydrologic and other information. The
boundaries of Hydrologic Units coincide with those of river basins but also
basins. The Hydrologic Unit code consistsof an eight digit code representing
the Region, Subregion, Accounting, and Cataloging Unit. The Regions,
Subregions and Accounting Units are aggregates of the Cataloging Units.
The Regions and Subregions are currently (1975) used by the U. S. Water
Resources Council for comprehensive planning, including the National
managing the National Water Data Network.
The boundaries as shown on the map have been adapted from "The
Catalog of Information on Water Data" (1972), "Water Resources Regions
and .,i r ,r the National Assessment of Water and Related land
Resc. -. U. S. Water Resources Council (1970), "River Basins of
the United States" by the U. S. Soil Conservation Service (1963, 1970), and
"River Basin Maps Showing Hydrologic Stations" by the Inter-
Agency Committee on Water Resources, Subcommittee on Hydrology
(1961). The boundaries also have been adopted by the Florida Department of
Natural Resources and provide a cataloging system for the five Water
Management Districts whose boundaries are hydrologic in nature.
The Cataloging Units shown will supplant the Cataloging Units
previously used by the U. S. Geological Survey in its Catalog of Information
of Water Data (1966-72) and as portrayed by Map Series 28, "Drainage
Basins in Florida," of the Florida Board of Conservation. The previous U. S.
Geological Survey Catalog-Indexing System was by map number and letter,
such as 12B.
Florida is within the South Atlantic-Gulf Region of the U. S. Water
Resources Council (03). The 8 Subregions (Nos. 7-14) in Florida are indicated
by color shading on the map and are named in the table. Presently 53
cataloging units arere recognized and listed in the table. Additional cataloging
or sub-units may be added as needed to delineate drainage basins of small
tributary streams, bays, or estuaries. Some Hydrologic Units, primarily the
Cataloging Units, given in the table include poorly defined coastal areas that
do not drain to a point, and intervening and partial drainage areas. The
areas of the Hydrologic Units given in the table include only those in
Monroe ... .
... ... 057
..... .. 05S
.... 71. 07
Palm Beach .
St. Johns .
Santa Rosa ...
.. ..... 105
HYDROLOGIC UNITS, NAMES, AND AREAS, IN SQUARE MILES, FOR THE SOUTH nL aTITi LLF RIL, IN FIRa fID
(Number in parenthesis following name refers todesignatonon .-- -- 1iM., ; -r -- .
PUL II AL SLBDuI IsIONt CuDt
The "Political Subdivision Code" provides a basis for cataloging and
retrieving hydrologic and other data by political units as well as by
The Political Subdivision Code has been adopted from "Counties and
County equivalents of the States of the United States" presented in Federal
Information Processing Standards Publication 6-2, issued by the National
Bureau of Standards (1973) in which each county or county equivalent is
identified by a 2-character State code and a 3-character county code. The
State code for Florida is 12. The county codes are shown in the
accompanying table but are not shown on the map.
Healy, Henry G.
1962 Piezometric surface and areas of artesian flou of the Floridan aquifer
in Florida, July 6-17, 1961: Florida Geol. Survey Map Series 4.
Hyde, Luther W.
1965 Principal aquifers in Florida: Florida Geol. Survey Map Series 16.
Kenner, W. E., Pride R. W., and Conover, C. S.
1967 Drainage basins in Florida: Florida Geol. Survey Map Series 28.
Langbein, W. B.
1960 (and Iseri, Kathleen T.), General introduction and hydrologsc definr-
tions: U. S. Geol. Survey Water-Supply Paper 1541-A, 29 p.
U. S. Department of Agriculture
1963 Atlas of river basins of the United States: Soil Conservation Service,
1970 Atlas of river basins of the United States: Soil Conservation Service,
U. S. Geological Survey
1951 Inter-Agency coordination of drainage area dita in Notes on Hydro-
logic Activities: Bulletin no. 4, November 19t1, 48 p.
1951 Surface water supply of the United States: U. S. Geol. Survey Water-
Supply Papers, U. S. Govt. Printing Office.
1951 Office of Water Data Coordination, South Atlantic and Gulf Coast
drainage area: Maps 9, 10, 11, 12.
1973 Office of Water Data Coordination, Catalog ofInformatien on Water
Data-1972 edition (21 volumes by Region, 86 maps showing location
of water-quality stations, and 86 maps showing location of streamflow
and stage stations): Reston, Va.
1975 Hydrologic Unit Map-1975, State of Florida, scale 1:500,000.
U. S. National Bureau of Standards
1973 Counties and county equivalents of the States of the United States:
U. S. Dept. Commerce, Federal Information Processing Standards
Pub. 6-2, 35 p.
U. S. Water Resources, Council
1970 Water resources regions and subregions for the national assessment
of water and related land resources: Washington, D.C., 188 p.
U. S. Weather Bureau
1961 River basn maps showing hydrologic stations in Notes an Hydrologic
Activities, Bull. 11. April 1961.
FLORIDA POLITICAL SUBDIVISION CODE
(Adapted from "Counties and county equivalents of the States of the United States")
Dr tang nUD reOntn fiataios
Iea. regp.mi to L n=- mg t,*tt
. 2,3 ,4
14 CHOCTAWHATCHEE, YELLOW, AND ESCAMBIA RIVERS .......... 6,491
01 Florida Panhandle Coastal .,.. 4,528
01 St. Andrew Bay, inflow and coastal area (11F) 1,351
02 Choetawhatchee Bay, inflow and coastal area 12B) .... .. .. 692
03 Yellow River Basin (12C) .. ... .. 1,365 .. .. 858
04 Blackwater River Basin (12D) ... .. 860 700
05 Escambia Bay,inflow andcoastalarea(12B-12E4) .. .. .. 542
06 Perdido River Basin (12F) .. .. ..... 925 .... ..... 252
07 Perdido Bay, inflow and coastal area (12F) ........ .. 133
02 Choctawhatchee River Basin ....... .......4,646 1,538
02 Pea River (12A3) ...... ... .. ........... 108
03 Choctawhatchee River below Pea River (12A4) .. .. .. ........ 1,430
03 Escambia River Basin .*.... .. .. 4,233 ... 425
04 Lower Conecuh River 12E1) .......... ... 8
05 Escambia River (12E4) ....... ....... 417
lIncludes area (sq. miles) in adjacent states.
2Includes area (sq. miles) in Florida only.
Note: To convert to square kilometers multiply square miles by 2.59.
DEPARTMENT OF NATURAL RESOURCES
BUREAU OF GEOLOGY
This public document was promulgated at a total
cost of $260.00 or a per copy cost of $.104 for the
purpose of disseminating hydrologic data.
o 10 20
89* 88a 87*T 86 85" 84* 83* 82* 81
FLORIDA GEO..OGIC SURVEY MAP SERIES
Region Accounting Unit
-ubrergon Le Cataloging Unit
Sub- Account a-
region gUnit ng Nameof Hydrologic Unit
No. mitr Unit
07 ALTAMAHA-ST. MARYS RIVERS .
02 St. Marys--Sat Rivers
04 St. Marys River Basin (09C)
08 T 7 1 Fr
01 St. Johns River Basin
01 St. Johns River Basin above Okalawaha River (09E1)
02 Okalawaha River Basin (09E2) ......
03 St. Johns River Basin below Oklawaba River (09E3) ....
02 East Florida Coastal
01 Coastal area between St. Johns River and Ponce de Leon Inlet (09F)
02 Coastal area between Pone de Inlet and Sebastian Ie d Sebtian Inlet (09F, 1
03 Coastal area Sebastian Inlet to St Lucie River (10A)
09 SOUTHERN FLORIDA
01 Lake Okeechobee inflow ..
01 Kissimmee River Basin (10B1)
02 Taylor Creek Basin and inflow to Lake Okeechobee from North (10B1)
03 Fisheating Creek Basin and inflow to Lake Okeechobee from Northwe ,,*i
02 Lake Okeechobeeob.
01 Lake Okeechobee (10B2)
02 Everglades and southeastern coastal area (10B2)
03 Florida Bay and the Florida Keys (10B2)
WESTERN COASTAL AREA
01 Peace River .
01 Peace River Basin 10D) ........
02 Myakka River Basin O (10E) ......
03 Charlotte Harbor and coastal area (10C)
02 Tampa Bay
01 Coastal area between Myakka and Manatee Rivers (10F)
02 Manatee River Basin (10F) .. ...
03 Little Manatee River Basin (1OF)
04 Alafia River Basin (10F)
05 Hillsboro River Basin (10H) .......
06 Tampa BayandCoastalareas(10F-10J) ...
07 Coastal area from Tampa Bay to Withlacoochee River (10J)
08 Withlacoochee River Basin (09G)..
11 SUWANNEE AND AUCILLA RIVERS.. ...... .......
01 Aucilla River and Coastal area
01 Waccasassa River and coastal area between Withlacoochee and
Suwannee Rivers (09H)
02 Coastal area between Suwannee and Aucilla Rivers (09K) ... ..
035 Auedla River Basin (11A) .......
02 Suwannee River
01 Suwannee River Basin above Withlacoochee River
excluding Alapaha River Basin (09J1)
02 Alapaha River Basin (09J2) ............ .
03 Withlacoochee River Basin (09J3)
05 Suwanee River Basin below Withlacoochee River excluding
Santa Fe River Basin (09J5) .1 ... ......
06 Santa Fe River Basin (09J6)
12 OCHLOCKONEE RIVER
00 Ochlcekonee River .. ......... .
01 St. Marks and Wakulla Rivers and coastal area between Aucilla and
Ochlockonee Rivers (11B) ....
03 Ochlockonee River Basin (11C) ...
13 APALACHICOLA, CHATTAHOOCHEE, AND FLINT RIVERS .
00 Apalacicola River .........
04 Lower Chattahoochee(llE2 ... ...... .
11 Apalachicola River (11E7) ... .. .. ..
12 ChipolaRiverBasin(IllE8) .. ....... ...
13 Coastal area between Ochlockonee and Apalachicola Rivers (11D) .
14 Apalachicola Bay coastal area and offshore islands (I1E7)
counting and cata-
ing unit boundaries