Water Flows and Nutrient Fluxes to the Southwest Coast of Everglades National Park, Florida

Project Proposal for 2001

IDENTIFYING INFORMATION

Project Title: Water flows and nutrient fluxes to the southwest coast of Everglades National Park, Florida
Subregion: 3
Project ID: FL-61400
Project Plan Manager: Victor Levesque
Email: levesque@usgs.gov
Phone: 813-884-9336 x167
Lead Organization(s): U.S. Geological Survey
Supporting Organization(s): Everglades National Park
County(s): Monroe
Start: FY 1996
End: FY 2001

DESCRIPTION AND METHODS

The U.S. Geological Survey (USGS) is conducting a study of water flows and nutrient fluxes for five tidally affected streams along the southwest coast of Everglades National Park (ENP). This study is to determine residual water flow and nutrient fluxes from the tidally affected reaches of the southwest Florida estuaries. This study is supported by the U.S. Geological Survey’s South Florida Ecosystem Program in collaboration with staff from the Everglades National Park, U.S. Army Corps of Engineers, and others. Data collected for the study at instrumented sites include:

• water level, as a variable for the calculation of cross-sectional area, mean water velocity, and discharge in stream channels,
• index velocity, using in-situ acoustic instrumentation for the calculation of mean water velocity and discharge in stream channels,
• measured discharge and velocity, using boat-mounted acoustic instrumentation to develop index-to-mean velocity relations,
• specific conductance, to indicate the presence of saltwater, to correlate with residual discharge, and to correct speed of sound values,
• water temperature, to correlate with water quality data, and to correct speed of sound values,
• water quality data, to calculate nutrient flux and acquire information on nutrient patterns and trends. Water quality data include total and dissolved concentrations for ammonia, nitrates and nitrites, organic nitrogen, phosphorus, ortho-phosphate, dissolved oxygen, pH, water temperature, specific conductance, and depth.

Three stations were established in January 1997 on the Broad, Harney, and Shark Rivers. Two additional stations were established in April 1999 on Lostman’s Creek and North River. The stations along the southwest coast were chosen based on historical information and a reconnaissance of the area. The Broad, Harney, Shark, and North Rivers may receive water from the Shark River Slough drainage area, while the Lostman’s River may receive water from the Shark River Slough and Big Cypress drainage area. Stations are visited on a four to six week schedule for data retrieval, calibration of in-situ instrumentation, water sample collection, and discharge measurements. In-situ instrumentation is checked for proper operation and conductance/temperature sensors are calibrated using quality controlled conductance standards. Water quality data are collected using a modified equal-width-increment (EWI) method. Three sites across the river at each station are used to collect a depth-integrated and horizontally integrated water sample using a 1-liter weighted-Teflon bottle and a 10-liter polyethylene churn. Water samples are analyzed according to USGS standard methods. A Hydrolab H2O is used to collect physical water quality data. Discharge measurements are made using an acoustic velocity profiler and associated software, and measurements are processed according to USGS methods.

Results have been successful and indicate that the Broad, Harney, and Shark Rivers 1999 mean residual discharges were very similar (approximately 400 to 500 cubic feet per second). The Harney and Shark River stations conductance can fluctuate from brackish to fresh with the tide during a portion of the wet season because of the station’s proximities to the Gulf of Mexico. Lostman’s Creek and Broad River stations are further upstream, away from the Gulf, and therefore can remain fresh (less than 500 microSiemens per centimeter) for almost the entire wet season and into the beginning of winter. The North River station conductance has become fresh, but the duration of time that the stream remains fresh is less than the Lostman’s and Broad River stations.

RESTORATION BENEFITS

Information from this study provides knowledge of residual water flow and nutrient flux along the southwest coast of Everglades National Park (ENP) to the Gulf of Mexico. This study’s data are being directly used, in conjunction with data from many other ongoing studies, to help determine the effects of changes in water deliveries to ENP on the southwest estuaries and Florida Bay ecosystems. Water flow and nutrient flux data are being and will continue to be used as input to hydrodynamic models of Florida Bay, the Gulf of Mexico, for calibration of hydrologic models of the south Florida mainland, and for water-budget determinations for south Florida. Hydrodynamic models and computations are substantially more dependable and reliable because of the availability of water flow, salinity, and nutrient flux data from this project. In turn, decisions regarding restoration activities based on scenario testing from such models and computations are also more reliable. The availability of long-term instantaneous and residual discharge and nutrient flux information is critical for quantitatively determining changes brought about by the restoration and modification of water drainage and storage in South Florida. Data from the instrumented stations are made available on the Internet through the South Florida Information Exchange (SOFIA) web site http://sofia.usgs.gov. Several short papers and abstracts have also been published to help disseminate the information generated by this study. A USGS Water Resources Investigations Report (WRIR) that describes all data collected at the Lostman’s Creek, Broad, Harney, Shark, and North Rivers, summarizes the methods and techniques used for the collection and analysis of these data is currently being written.

WORK PLAN FY2001

1. Process and analyze data.
2. Finalize velocity-stage-discharge relations for Lostman’s Creek and North River stations.
3. Finalize nutrient flux relations for Lostman’s Creek and North River stations.
4. Complete report for southwest coast stations.

EMPLOYEE REQUIREMENTS AND COMMITMENTS TO THIS STUDY

Victor Levesque, Hydrologist/Engineer
Kathleen Hammett, Surface Water Specialist
Yvonne Stoker, Water Quality Specialist

DELIVERABLES

FY2001		Water Resources Investigation Report (WRIR) "Water flows and Nutrient Fluxes along the southwest Coast of Everglades National Park", 1997-2000.
		Provide data to ENP personnel on CD-ROM.

BIBLIOGRAPHY

Levesque, Victor A., 1999, Synopsis of flows and nutrient fluxes to the southwest coast of Everglades National Park, Florida, 1996-99, U.S. Geological Survey Program on the South Florida Ecosystem - Proceedings of South Florida Restoration Science Forum, May 17-19, 1999, Boca Raton, Florida: U.S. Geological Survey Open-File Report 99-181, p. 62-63.

Levesque, Victor A., 1998, Water flows and nutrient loads to the southwest coast of Florida: Abstract, Proceedings of the Florida Bay Science Conference, Miami, Florida, May 12-14, 1998.

Levesque, Victor A., 1997, Water flows and nutrient loads to the southwest coast of Florida - A Study Plan: U.S. Geological Survey Fact Sheet FS-179-96.

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