U.S. Department of the Interior

U.S. Geological Survey

CAPE SABLE

C-111

FLORIDA KEYS

Taylor Slough

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25°15¢

81°00¢ 80°45¢ 80°30¢

FLORIDA BAY

Location

of Study Area

EVERGLADES

NATIONAL PARK

GULF OF MEXICO

EVERGLADES NATIONAL PARK BOUNDARY

EVERGLADES NATIONAL PARK BOUNDARY

MONITORING STATION

EXPLANATION

ATLANTIC OCEAN

McCormick

Creek

Taylor River

Mud Creek

Trout Creek

West

Highway

Creek

Magnitude and Distribution of Flows 

into Northeastern Florida Bay

Concerns with Florida Bay 

Ecosystem

Changes in water-management 

practices have been made to 

accommodate a large and rapidly 

growing urban population along the 

Atlantic Coast and to meet the 

demand for intensive agricultural 

activities. These changes have 

resulted in a highly managed

hydrologic system consisting of 

numerous canals, levees, control 

structures, and pumping stations that 

have altered the hydrology of the 

Everglades and Florida Bay 

ecosystems. Over the past decade, 

Florida Bay has experienced sea-grass 

die-off and algal blooms, which are 

indicators of ecological change 

attributed primarily to the increase in 

salinity and nutrient content of bay 

waters. Because plans are to restore 

sheetflow in the Everglades wetlands 

to its natural state, water managers 

anticipate a change in the magnitude 

and timing of freshwater exiting the 

mainland through the creeks that cut 

through the embankment or as 

sheetflow into Florida Bay.

Flow through the mangrove zone 

into northeastern Florida Bay is 

controlled by water levels in the 

Everglades wetlands, regional wind 

patterns, and to a minor extent, tidal 

fluctuations. Restoration of the 

Florida Bay ecosystem requires an 

understanding of the linkage between 

the salinity, quality of the bay 

environment, and the amount of 

freshwater flowing into the bay.

In 1995, the U.S. Geological 

Survey (USGS) initiated the South 

Florida Ecosystem Program (now 

known as the South Florida 

Place-Based Program). This program 

was established as a collaborative 

effort by Federal agencies working 

with State and local agencies to 

resolve land-use demands and watersupply issues in southern Florida. As 

part of this program, the USGS is 

presently conducting a study to measure flows into Florida Bay from the 

mainland through the major creeks 

along the northeastern coast. The 

results of this study will provide 

scientists with essential information 

from along the mangrove zone where 

data were not previously available.

Monitoring Stations

Freshwater flow into northeastern Florida Bay is mostly 

confined to several creeks, 

except during extreme high-water 

conditions when sheetflow could 

occur in low-lying mangrove areas 

between the creeks. Five monitoring 

stations in the mangrove zone along 

the northeastern coast of Florida Bay 

(fig. 1) were selected to determine the 

magnitude and distribution of flows 

into the bay. The West Highway 

Creek, Trout Creek, Mud Creek, 

Taylor River, and McCormick Creek 

stations are located along a mangrove 

zone, spanning about 20 miles across 

the northeastern edge of Florida Bay. 

USGS Fact Sheet FS-030–00

May 2000

Figure 1. Location of monitoring stations in northeastern Florida Bay.

South Florida Place-Based Program
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ACOUSTIC LINE VELOCITY, IN FEET PER SECOND

MEAN VELOCITY, IN FEET PER SECOND

Rating

Measured

Stage, water velocity, temperature, 

and salinity data were collected from 

these stations. Figure 2 shows a 

typical USGS monitoring station 

(Taylor River) in Florida Bay.

Acoustic Velocity

Time-series records of acoustic 

velocity were collected and used with 

discharge measurements to establish 

an acoustic-velocity to mean-velocity 

relation for the creeks. The technique 

used to describe the velocity relation 

is a least squares regression model in 

the single or multiple form, depending 

on the number of identified significant 

variables. The model uses the following equation:

where is mean channel water 

velocity, Vl

 is acoustic line velocity, 

X1 and X2 represent regression coefficients, H is stage, and C is a constant.

The acoustic line velocity is the 

predominant variable, and in most 

cases, the only variable needed for the 

description of the velocity relation. 

Occasionally, stage plays a significant 

role in describing the relation and 

needs to be included in the above 

equation. A typical acoustic-to-mean 

velocity relation for one of the

monitoring stations (Trout Creek) is 

shown in figure 3.

V Vl X1HX2 = ( ) + C

V

Flows into Northeastern 

Florida Bay

Velocity and area relations 

developed for each monitoring station 

were used to calculate 15-minute 

time-series discharge data for all 

gaged creeks along the coastline. In 

other areas, most estuarine creeks 

present flow patterns that include the 

reversal of flow direction during flood 

and ebb tides. In the creeks that 

discharge into Florida Bay, this

typical tidal signature is either 

nonexistent or substantially altered by 

wind forces. The flow direction for 

stations monitored in northeastern 

Florida Bay is mainly dictated by the 

wet- or dry-season conditions of the 

Everglades wetlands and the regional 

wind speed and direction. Commonly 

used data filters were not used for net 

flow calculations because of these 

flow patterns. Monthly mean values 

of discharge were used to account for 

storage and to determine net flows for 

all monitoring stations. 

East-West Flow Distribution

Discharge results for the five 

stations indicated that the majority of 

flow into Florida Bay occurs east of 

the Taylor Slough drainage area. 

Discharge was least for McCormick 

Creek (3 percent of total) and greatest 

for Trout Creek (67 percent of total) 

during May 1996 through April 1998. 

The percentages of freshwater contributions for the five monitoring 

stations are shown in figure 4.

Figure 2. U.S. Geological Survey monitoring station (Taylor River) in 

Florida Bay. 

Figure 3. Velocity relation for Trout Creek monitoring station. 
West Highway Creek (14%)

Trout Creek (67%)

Taylor River (9%)

Mud Creek (7%)

McCormick Creek (3%)

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JUNE 1997

DISCHARGE, IN CUBIC FEET PER

SECOND (NEGATIVE VALUES INDICATE

REVERSE FLOW)

SALINITY, IN PARTS PER THOUSAND

Discharge

Salinity

EXPLANATION

MEAN DISCHARGE, IN CUBIC

FEET PER SECOND

(NEGATIVE VALUES INDICATE

REVERSE FLOW)

McCormick

Creek

Taylor

River

Mud

Creek

Trout

Creek

West

Highway

Creek

MAY 1996 TO APRIL 1997

McCormick

Creek

Taylor

River

Mud

Creek

Trout

Creek

West

Highway

Creek

MAY 1997 TO APRIL 1998 EXPLANATION EXPLANATION

Wet season

(May-Oct)

Wet season

(May-Oct)

Dry season

(Nov-Apr)

Dry season

(Nov-Apr)

500

400

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Seasonal Flow Variations

About 80 percent of the total 

freshwater discharge into northeastern Florida Bay occurs during the 

wet season (May-October). A very 

distinct transition between brackish 

water and freshwater occurs at the 

mangrove zone near the beginning of 

the wet season. This brackish-water/

freshwater transition period was 

apparent at the Taylor River monitoring station in June 1997 (fig. 5). 

Substantial El Niño effects on dryseason flows at all of the monitoring 

stations in northeastern Florida Bay 

are evidenced by a mean discharge 

increase from about 41 cubic feet per 

second in 1996-97 to 273 cubic feet 

per second (average for all stations) in 

1997-98. Regional wind patterns and 

shallow water depth in the Everglades 

wetlands following El Niño are the 

probable cause for a divergence in 

flow pattern between McCormick 

Creek and the other monitoring 

stations. The wet- and dry-season 

freshwater discharges (1996-97 and 

1997-98) for each of the five 

monitoring stations are shown in 

figure 6.

Figure 6. Wet- and dry-season freshwater discharges through all monitoring stations in northeastern Florida Bay.

Figure 5. Brackish water (dry season) to freshwater (wet season) 

transition at the Taylor River monitoring station, June 1-30, 1997.

Figure 4. Estimated freshwater contribution of stations 

monitored in northeastern Florida Bay.
1,000

800

600

400

200

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ND J FMAM J J ASOND J FMAMJ J ASOND J FMA

MEAN DISCHARGE, IN CUBIC FEET PER SECOND

(NEGATIVE VALUES INDICATE REVERSE FLOW)

1995 1996 1997 1998

Trout Creek

McCormick Creek

Taylor River

Mud Creek

West Highway Creek

EXPLANATION

Three main flow signatures were 

identified when comparing flows at 

the monitoring stations in northeastern Florida Bay (fig. 7). The most 

important is the magnitude of 

discharges at Trout Creek, which 

carries about 67 percent of the total 

freshwater entering northeastern 

Florida Bay (fig. 4). The other two 

signatures are the drifting of 

McCormick Creek following the 

El Niño event of 1997-98 and the 

absence of net negative flows at West 

Highway Creek. McCormick Creek 

probably disconnects from the Taylor 

Slough drainage basin during lowwater conditions in the wetlands. The 

observed east-west flow distribution, 

and especially the magnitude of flows 

through Trout Creek, suggest that 

freshwater flow in the Everglades 

wetlands along Taylor Slough may be 

farther to the east than previously 

thought. Further evaluation of

discharge and salinity patterns would 

be necessary to extend the analysis 

period beyond the influence of 

extreme hydrologic events (such as 

El Niño) and to assess both short- and 

long-term flow trends in northeastern 

Florida Bay.

Data Releases

Mean daily values (of ninety-six 

15-minute-interval readings) of 

discharge, stage, water velocity, 

temperature, and salinity for the five 

monitoring stations are posted on the 

USGS Sofia Web Page for public use 

and retrieval (http://sofia.er.usgs.gov). 

Records will be updated on a 

quarterly schedule for the duration of 

the project. Any questions or requests 

should be directed to the USGS 

Miami Subdistrict office.

By Eduardo Patino and Clinton Hittle

For more information

Clinton Hittle

9100 NW 36th Street

Miami, FL 33156

phone: (305) 717-5800

fax: (305) 717-5801

e-mail: cdhittle@usgs.gov

Eduardo Patino 

3745 Broadway

Live Oak Building, Suite 301

Fort Myers, FL 33901

phone (941) 275-8448

fax: (941) 275-6820

e-mail: epatino@usgs.gov

Figure 7. Mean monthly flows for all monitoring stations in northeastern Florida 

Bay, November 1995 to April 1998. 

Discharge measurement at Trout Creek Monitoring station inspection