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TIDAL WATER BOUNDARIES*
George M. Cole**
This Article describes the boundaries between riparian up-
lands and publicly owned tidally affected waters. It includes legal
definitions of these boundaries, a discussion of which waters are
considered publicly owned, and a description of surveying tech-
niques used for locating such boundaries.
Water boundaries are perhaps the oldest and most widely used
of man's boundaries. Yet despite this long history of usage, water
boundaries are probably, in today's society, the most frequently and
bitterly contested of all boundaries. The edge of water forms an ex-
cellent natural boundary in that it is easily defended and easily rec-
ognized. However, when landowners attempt to make precise loca-
tions of water boundaries, complex technical and legal quagmires
may result. This is primarily due to the fact that the land-water in-
terface is dynamic. The surfaces of most water bodies are constantly
changing due to tides and meteorological conditions. In addition, the
shorelines in many areas constantly change due to erosion and accre-
tion caused by waves and currents. Therefore, unlike other bounda-
ries, one must consider a third dimension height and a fourth di-
mension time when dealing with water boundaries. Thus, these
unique boundaries must be considered in a different manner than
conventional, two dimensional land boundaries. Consequently,
unique laws and techniques have developed for defining and locating
Legal Definitions of Tidal Boundaries
The definitions of tidal boundaries currently recognized in most
areas of the United States have gradually evolved in the Anglo-Amer-
ican common law. Perhaps the earliest mention of such boundaries in
English literature was by Thomas Digges, an engineer, surveyor and
lawyer during the reign of Queen Elizabeth I, in a book entitled
Much of this Article has been abstracted from a manuscript now in production at
Landmark Enterprises for the Second Edition of Water Boundaries.
** George M. Cole, P.E., P.L.S. President, Florida Engineering Services Corporations,
Engineers-Planners-Surveyors, Tallahassee, Florida.
Stetson Law Review
Proofs of the Queen's Interest in Land Left by the Sea and the Salt
Shores Thereof. This treatise, written about 1568, formed the basis
for the Crown's claim to the submerged lands of the kingdom. In that
text, Digges suggested that the Crown owned the "foreshore," which
is the area between high and low tides, but was not more specific.
In the following century, Lord Chief Justice Matthew Hale es-
poused the public trust doctrine, as put forth by Digges, in the trea-
tise De Jure Maris, written about 1666. In that writing, Hale con-
cluded that the foreshore, which is overflowed by "ordinary tides or
neap tides, which happen between the full and the change of the
moon," belonged to the Crown.
With our knowledge of the tides today, it is obvious that Lord
Hale was incorrect in equating "neap tides" with "ordinary tides." At
the very least, his definition was ambiguous. In 1854, this definition
was clarified in English common law by the case of Attorney General
v. Chambers.1 The Chambers case, reflecting tidal theory developed
after Hale's writings, ruled that the ordinary high water mark was to
be determined by "the average of the medium tides found in each
quarter of a lunar evolution during the year [which line] gives the
limit, in the absence of all usage, to the rights of the Crown on the
In the United States, there apparently was no case law giving
technical clarification to the boundary until 1935 and the United
States Supreme Court's landmark decision in Borax Consolidated v.
City of Los Angeles.3 In essence, this decision called for application
of scientific and statistical techniques for precisely defining the
In view of the definition of the mean high tide, as given by the
United States Coast and Geodetic Survey, that "Mean high water at
any place is the average height of all the high waters at that place
over a considerable period of time," and the further observation that
"from theoretical considerations of an astronomical character" there
should be "a periodic variation in the rise of water above sea level
having a period of 18.6 years," the Court of Appeals directed that in
order to ascertain the mean high tide line with requisite certainty in
fixing the boundary of valuable tidelands, such as those here in
question appear to be, "an average of 18.6 years should be deter-
1. 43 Eng. Rep. 486 (1854).
2. Id. at 489.
3. 296 U.S. 10 (1935).
Tidal Water Boundaries
mined as near as possible." We find no error in that instruction.'
As this language demonstrates, the Borax decision applied mod-
ern technical knowledge and set forth a workable technique for pre-
cisely locating the boundary in question. At the time of this writing,
this case still prevails in United States common law.
Case law in the various coastal states has, in the main, followed
the English common and statutory law and its updated definitions as
set forth in the Borax decision. Sixteen states have followed this
course.5 It should be noted that six Atlantic Coast states recognize
the mean low water line as the sovereign/upland boundary line.6 Il-
lustrations are found in the laws of Maine and Massachusetts, where
a colonial ordinance of 1641-47 provided for private ownership along
tidal waters to extend to the "low water mark where the sea doth not
ebb above one hundred rods, and not more wheresoever it ebbs
It should be noted that there are exceptions to the above gener-
alizations. One such exception involves sovereign grants preceding
American interest. In Spanish and Mexican grants, for example, it
has been held that the limit of ownership is controlled by old Spanish
law contained in Las Siete Partidas, written in the thirteenth cen-
tury and tracking the Roman Institutes of Justinian, written in the
sixth century.8 A translation of a portion of that code reads as fol-
lows: "The sea-shores, that is, the shore as far as the waves go at
furthest, was considered to belong to all men. The sea shore ex-
tends as far as the greatest winter flood runs up."'
Some states, such as Florida, have codified their common law on
tidal boundaries. The state's Coastal Mapping Act"1 declares that
"the mean high water line along the shores of land immediately bor-
dering on navigable waters is recognized and declared to be the
4. Id. at 26-27.
5. Alabama, Alaska, California, Connecticut, Florida, Georgia, Maryland, Mississippi,
New Jersey, New York, North Carolina, Oregon, Rhode Island, South Carolina, Texas, and
Washington. G. COLE, Tidal Boundary Surveying, in TECHNICAL PAPERS, AMERICAN CONGRESS
ON SURVEYING AND MAPPING 236, 239 (1977); See generally Maloney & Ausness, The Use and
Legal Significance of the Mean High Water Line in Coastal Boundary Mapping, 53 N.C.L.
REV. 185 (1974).
6. Delaware, Maine, Massachusetts, New Hampshire, Pennsylvania, and Virginia. Malo-
ney & Ausness, supra note 5, at 204-206.
7. 1660 Mass. Bay Colony Public Laws.
8. See Luttes v. State, 324 S.W.2d 167, 176 (Tex. 1958).
9. INSTITUTES OF JUSTINIAN, 158, 159 n.3 (T. Sanders ed. 1876).
10. FLA. STAT. 177.25-.40 (1989).
Stetson Law Review
boundary between the foreshore owned by the State in its sovereign
capacity and upland subject to private ownership."" The statute also
defines the mean high water line using the Borax decision."
WHICH WATERS ARE SOVEREIGN?
An obvious question arising when one is defining the boundary
between sovereign waters and private uplands is: Which waters are
sovereign? A simplistic answer to the question is: navigable waters.
However, that is not an explicit answer since there are many defini-
tions of navigability. In addition, there are some water bodies that
are navigable-in-law although not necessarily navigable-in-fact, while
others are navigable-in-fact although not necessarily sovereign.
In nontidal waters, navigability for title purposes generally is a
question of navigability-in-fact. In Florida, for example, recent case
law" offers specific clarification to that state's definition of nontidal
waters. The state supreme court held that "Florida's test for naviga-
bility is similar, if not identical, to the federal title test."" The fed-
eral title test was defined as being "based on the body's potential for
commercial use in its ordinary and natural condition.""1
In tidal waters, however, navigability for title purposes appears
to be not always based on navigability-in-fact. In some states, public
ownership appears to extend to submerged lands subject to the ebb
and flow of the tide, regardless of actual navigability. An excellent in
depth article on this subject indicates that in Louisiana, Maryland,
Mississippi, New Jersey, New York, and Texas, state ownership ex-
tends to all waters subject to tidal ebb and flow; while in California,
Connecticut, Florida, North Carolina, and Washington, public owner-
ship is based on navigability-in-fact." The same article states that
"Alabama, Oregon and South Carolina find tidal watercourses prima
facie navigable and thus presume the land beneath the watercourses
to be sovereign land, but this presumption of state ownership may be
rebutted by a finding of nonnavigability.""'
The preponderance of Florida case law appears to support the
11. Id. 177.28(1).
12. Id. 177.27(15).
13. Odom v. Deltona Corp., 341 So. 2d 977 (Fla. 1976).
14. Id. at 988.
16. Maloney & Ausness, supra note 5, at 209-216.
17. Id. at 216.
Tidal Water Boundaries
opinion reflected in this article. For example, Clement v. Watson'"
states that waterses are not under our law regarded as navigable
merely because they are affected by the tides."' Another case states
this opinion in the same words.0 A more recent case, Board of Trust-
ees v. Wakulla Silver Springs Co.,21 also reflects this opinion.22 Fur-
thermore, the navigability-in-fact position is implied in section
177.28 of the Florida Statutes.28
As mentioned above, the State of Mississippi has generally been
considered to be an ebb and flow state. However, in Cinque Bambini
Partnership v. State,"2 there was a challenge in that state as to
whether all tidally affected waters are sovereign regardless of naviga-
bility-in-fact. The author served as the state's expert in that case. At
the chancery court level and in the Mississippi Supreme Court, this
case was decided in favor of ebb and flow. Salient excerpts from the
Mississippi Supreme Court opinion are as follows:
The early federal cases refer to the trust as including all lands
within the ebb and flow of the tide ... [and] it is our view that as a
matter of federal law, the United States granted to this State in
1817 all lands subject to the ebb and flow of the tide and up to the
mean high water level, without regard to navigability [There-
fore,] so long as by unbroken water course when the level of the
waters is at mean high water mark one may hoist a sail upon a
toothpick and without interruption navigate from the navigable
channel/area to land, always afloat, the waters traversed and the
lands beneath them are within the inland boundaries we consider
the United States set for the properties granted the state in trust.""
The case was appealed to the United States Supreme Court,26
which affirmed the state court, ruling that all coastal states once
owned all lands over which tidal waters flow, and that Mississippi
still does.2 The opinion noted that this ruling "will not upset titles in
18. 63 Fla. 109, 58 So. 25 (1912).
19. Id. at 112, 58 So. at 26.
20. City of Tarpon Springs v. Smith, 81 Fla. 479, 498, 88 So. 613, 620 (1921).
21. 362 So. 2d 706 (Fla. 1978).
22. Letter from J. Kendrick Tucker, Florida Deputy Attorney General, to George M. Cole
23. FLA. STAT. 177.28(1) (1989). See supra text accompanying note 11.
24. 491 So. 2d 508 (Miss. 1986), aff'd sub nom. Phillips Petroleum Co. v. Mississippi, 484
U.S. 469 (1988).
25. Id. at 513, 514, 515.
26. Phillips Petroleum Co. v. Mississippi, 484 U.S. 469 (1988).
27. Id. at 473.
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all coastal states [since it] does nothing to change ownership rights in
states which previously relinquished a public trust claim to tidelands
such as those at issue here."" Therefore, it is presumed that the rul-
ing has no net effect in those states, such as Florida, that have estab-
lished navigability-in-fact case law.
TECHNIQUES FOR LOCATING TIDAL BOUNDARIES
The tide is the alternating rise and fall in sea level produced by
the gravitational force of the moon and the sun. Other nonastronomi-
cal factors such as meteorological forces, ocean floor topography, and
coast line configuration also play an important role in shaping the
To clearly see the mechanics of the tide producing forces, one
should visualize a bulge or wave of water directly under the moon.
This water has been lifted up by the gravitational pull of the moon
on the fluid water. On the side opposite the moon, the greater
centrifugal force as the earth and moon spin causes another high
water. These two bulges of water follow the moon in its revolution
about the earth.
Since the rotational period of the moon about the earth is 24.84
hours, these moving high waters take the form of sine waves with
periods of 12.42 hours. Likewise there is a sine wave with a period of
12.00 hours following the apparent rotation of the sun.
The sea level rises caused by many other relationships between
the sun, earth, and moon may also be depicted as sine waves of a
specific period. For example, the elliptical orbit of the moon about
the earth results in a constituent wave with a period of 27.5 days with
highest water at the time of perigee (when the moon is closest to the
earth) and lowest water when the moon is the greatest distance away.
The longest of such constituent periods normally considered is that
associated with the regression of the moon's nodes, which has a pe-
riod of 18.6 years.
The resultant tide is the composite, or algebraic sum, of all the
above mentioned constituent cycles. It is noteworthy that when the
high water of more than one constituent is in phase, tides higher than
28. Id. at 483.
29. U.S. DEP'T OF COMMERCE, NATIONAL OCEAN SURVEY AGENCY, OUR RESTLESS TIDE
Tidal Water Boundaries
normal occur. Such is the case twice a month when the moon and
sun's principal constituents are in phase. This occurs near the time of
the new and full moon when the earth, moon, and sun are in a line
and produces the so-called spring tides. Neap tides are those which
occur at the time of the quarter moons when the sun and moon are at
ninety degrees to each other as measured from the earth. Their re-
spective following waves are then out of phase and result in lower
In most areas of the world, semi-diurnal (or twice daily) tidal
oscillations predominate. In some areas, however, only one high water
and one low water per tidal day are experienced for most of the
month. These are called diurnal tides. In the United States, the west-
ern portion of the Gulf of Mexico is a good example of a diurnal tide
area. Apparently, this is the case because the Gulf of Mexico Basin
has a natural period of oscillation of approximately twenty-four
hours which reinforces the diurnal tide producing forces.
Tidal Datum Planes
A tidal datum is a plane of reference for elevations that is based
upon tidal height. Considering the above discussion, it is obvious that
to be statistically significant, a tidal datum should include all of the
periodic variations in tidal height. Therefore, a tidal datum is usually
considered to be the average of all occurrences of a certain tidal ex-
treme for a period of nineteen years." Such a period is called a tidal
As an example of a tidal datum, mean high water is defined as
the average height of all the high waters occurring over a period of
nineteen years. Likewise, mean low water is defined as the average of
all of the low tides over a nineteen-year tidal epoch. Mean tide level
or half tide level is the plane halfway between mean high and mean
In addition to the above, there are two other datum planes of
significance to water boundaries. Mean higher high water is the aver-
age of the higher of the high tides occurring each day. Mean lower
low water is the average of the lower of the low tides occurring each
day. Both of these averages are calculated over a tidal epoch.
From the foregoing, it may be seen that the primary determina-
30. The exact time is 18.6 years, rounded to the nearest whole year to include a multiple
of the annual cycle associated with the declination of the sun.
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tion of a tidal datum involves the relatively simple determination of
the arithmetic mean, or average, of all the occurrences of a certain
tidal extreme over a tidal epoch. In practice, this is usually accom-
plished by computing mean values of the various tidal extremes for
each calendar month, and then annual mean values by averaging the
twelve monthly means for each extreme for each calendar year. Fi-
nally, the mean values for the tidal epoch used are determined by
averaging the annual mean values for the nineteen years comprising
It should be noted that a tidal datum is a local phenomenon be-
cause of numerous local forces shaping the tide. There can be consid-
erable difference in the elevation of a tidal datum from point to point
in even the same general vicinity.81 Therefore, a tidal datum should
be determined in the immediate area of its intended use.
Secondary Datum Determinations
Because of the local variation in the elevation of a tidal datum, it
is obvious that datum points would have to be determined quite
densely along a coast for precise boundary determination. It is
equally obvious that it would be impractical to do so if nineteen years
of observation are necessary at each desired datum point. Fortu-
nately, methods have been developed for correcting short term obser-
vations to the equivalent of a nineteen-year mean. The most satisfac-
tory method to achieve this is by simultaneous observations at the
desired point and at a control station at which nineteen-year mean
values are known. The average of the observed tidal extremes may
then be reduced to a value equivalent to a nineteen-year mean by a
mathematical correlation process using a ratio of tide ranges ob-
served at the two stations.s3
Linear Interpolation Between Tide Stations
In some situations, such as along open coasts without significant
breaks, a valid datum may be determined by linear interpolation be-
tween adjacent tide stations. This may be accomplished by determin-
ing the elevation, in relation to a common geodetic datum, of the
31. G. COLE, supra note 5, at 236.
32. G. COLE, Proposed New Method for Determining Tidal Elevations in Intertidal
Zones, in TECHNICAL PAPERS, AMERICAN CONGRESS ON SURVEYING AND MAPPING, 235 (1981). See
generally H. MARMER, TIDAL DATUM PLANES Special Publication No. 135 (U.S. Coast and Geo-
detic Survey, rev. ed. 1951).
Tidal Water Boundaries
tidal datum planes at the tide station on either side of the desired
site. The elevation at the desired site may then be determined by
proportioning the difference in elevation of the tidal datum at the
two sites, according to the distance between the two stations and the
It is cautioned that invalid results may result from interpolation
in estaurine or riverine areas or along breaks in an open coastline. In
such areas, the establishment of a secondary datum by simultaneous
tidal observations is recommended.
Sea Level Changes
As mentioned in the previous section, a tidal datum is defined as
an average over a nineteen-year period known as a tidal epoch. Tra-
ditionally, for all datum values published by the National Ocean Ser-
vice, all data are referred to a specific epoch called the National
Tidal Datum Epoch. A specific nineteen-year period is used since ap-
parent nonperiodic variation in mean sea level is noted from one
nineteen-year period to another. It is not known if these trends are
truly nonperiodic or a part of some long term oscillation. These
nonperiodic changes are apparently due to "glacial-eustacy, thermal
volumetric changes, vertical land movements, and both climatological
and oceanographic trends."33
Sea level monitoring has indicated a worldwide trend of contin-
ual rise in sea level. To correct for this rise in the United States, a
new epoch has historically been adopted every two or three decades
when significant change has occurred. At such times, adjustments are
made to all datum elevations. In effect, a quantum jump occurs in
the elevations of all tidal datum planes for stations published by the
National Ocean Service at those times. An example of this occurred
in 1981, when the National Ocean Service retired the epoch of 1941-
1957, and adopted the period 1960-1978 as the National Tidal Datum
In recent years, sea level has been rising at an average rate of
0.0066 feet per year in the United States.s' Some sections of the coast
have a much higher rate. An example of this is the Freeport, Texas
33. S.D. HICKS, H.A. DEBAUGH & L.E. HICKMAN, SEA LEVEL VARIATIONS FOR THE UNITED
STATES 1855-1980, at 2 (1983).
34. Hicks & Hickman, United States Sea Level Variations Through 1986, SHORE AND
BEACH, July 1988, at 5.
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area with an average rise of 0.046 feet per year."3
Obviously, in areas such as the Texas coast and even in areas
with average rates of sea level rise, a significant difference can exist
between an elevation computed on the National Tidal Datum Epoch
and a datum computed on the most recent 19 years. Therefore, it
may sometimes be more desirable to recompute data on a more cur-
rent epoch than use published data computed on the National Tidal
Techniques for Locating Tidal Datum Lines
The distinction between the datum or elevation of a tidal bound-
ary and the tidal datum line is an important concept in water bound-
aries. A tidal datum will remain constant, for practical purposes, at a
given location over the years. On the other hand, a tidal datum line,
which is the intersection of the datum with the rising land, may vary
considerably as the land erodes or accretes under the same elevation
of water. Therefore, the line can be ambulatory and should be related
to a specific point in time.
Once a local tidal datum has been established, there are basically
three methods that may be used for locating the corresponding tidal
datum line in the area around the datum determination. These are
the staking method, the topographic method, and tide-coordinated
Often the most practical of these is the staking method. This
method allows the water itself to define the line. As an illustration of
this method, assume that the correct reading on a staff for a tidal
datum has been previously determined. On a tide that is predicted to
reach or exceed that value, the staff should be observed. When the
water level reaches the predetermined staff reading, a signal is given.
At the signal, personnel in the area around the staff place a series of
stakes at frequent intervals along the incoming edge of the water.
These stakes, defining the tidal datum line, may then be mapped by
traverse, range and bearing, or other conventional surveying proce-
dures. The obvious advantage of this method is that the surveyor ac-
tually sees the line on the ground and can identify each inflection
The topographic method consists of assuming that the local da-
35. S.D. LYLES, L.E. HICKMAN & H.A. DEBAUGH, SEA LEVEL VARIATIONS FOR THE UNITED
STATES 1855-1986, at 9 (1988).
Tidal Water Boundaries
tum line is a topographic contour in the immediate area around the
datum determination. This contour line is then located by leveling,
and mapped by conventional horizontal surveying procedures. Cau-
tion is necessary with this method since only points on the line are
being located, as contrasted with a continuous line in the staking
method. Unless care is taken, it is easy to miss significant breaks and
inflections in the line.
Tide coordinated aerial photography can be used to map a tidal
datum line when the tidal datum line is not obscured by dense vege-
tation. This method involves the use of aerial photography coordi-
nated by an observer on the ground watching a tide staff. At the pre-
cise time that the tide reaches the predetermined staff reading for
the tidal datum, the observer signals the aircraft and the water-land
interface is photographed on black and white infrared film. The in-
frared photography graphically depicts the interface between the
water and land if the land is relatively dry.
Another means of mapping the approximate location of a tidal
datum line is by interpolation between known points on the line by
use of aerial photography.3 This is usually accomplished by placing
aerial targets on the known points as ground truth points. The line
between these points is then interpolated using the tones and tex-
tures seen in the photography. Color infrared, natural color, as well
as black and white photography have all been used with success in
various areas. This may be the most practical means of mapping the
line in many heavily vegetated marshlands.
Sources of Tidal Data
A primary source of tidal data is the National Ocean Service
(NOS) of the National Oceanic and Atmospheric Administration
(NOAA) of the United States Department of Commerce. That agency
and its predecessors, the United States Coast Survey, the United
States Coast and Geodetic Survey, and the National Ocean Survey,
have monitored tides along our nation's coastline since 1855. The
data have historically been used by those agencies in connection with
hydrographic surveys of the coast and for preparing predictions of
NOS maintains a network of permanent tide stations. In addi-
36. G. COLE, Where Oil, Water, Surveying and Photogrammetry Mix, in TECHNICAL PA-
PERS, AMERICAN CONGRESS ON SURVEYING AND MAPPING 322 (1982).
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tion, the agency has established a large number of short term stations
in connection with many years of hydrographic surveys or in coopera-
tive programs with various states for coastal boundary purposes. For
all of these stations, the NOS publishes station reports containing
descriptions of the bench marks associated with the stations and ele-
vations for those bench marks relating to various tidal datum planes.
That information, as well as the source data and summaries used in
preparing it is available from the agency.
In Florida, the Bureau of Survey and Mapping of the Depart-
ment of Natural Resources also maintains a repository of the tide
station reports published by the NOS for Florida. This information is
also available in a computer data base called Land Boundary Infor-
mation System (LABINS), which is maintained by the Florida Re-
source and Environmental Analysis Center of Florida State Univer-
sity. LABINS may be easily accessed by telephone by use of a
computer equipped with a modem and telecommunications software.
Requirements of Florida Coastal Mapping Act
The Florida Coastal Mapping Act37 also affects techniques for
locating tidal boundaries in Florida with its requirement that uni-
form specifications be used for all tidal surveys in the state. It re-
quires that all maps or surveys purporting to establish local tidal da-
tums or to determine the location of the mean high water line or
mean low water line be made in accordance with provisions of the
statute, to be admissible as evidence in any court, administrative
agency, political subdivision or tribunal in the state. A key require-
ment of administrative rules promulgated in accordance with the
statute" is that the Department of Natural Resources be contacted
prior to the undertaking of a tidal survey to obtain approval of proce-
dures to be used. At the completion of the project, the Department
must also be provided any revisions made in the proposed proce-
dures, a description of the location and tidal elevations of any bench
marks set in the survey, and a copy of the survey plat.
37. FLA. STAT. 177.25-.40 (1989). See supra text accompanying notes 10-12.
38. FLA. ADMIN. CODE ANN. ch. 16-3 (1982 & Supp. 1985).