U.S Geological Survey, South Florida Ecosystem Program: Place-Based Studies

Project: Water Flows and Nutrient Fluxes to the Southwest Coast of Everglades National Park (# FL61400)

Web Site: http://sofia.usgs.gov/projects/nutrient_load

Location: Central Everglades and Southwest Coast / Big Cypress; Monroe County

Principal Investigator: Victor A. Levesque, levesque@usgs.gov, 813.884.9336x167

Project Personnel: Paul Boetcher, boetcher@usgs.gov, 813.884.9336x151; Tim O'Hare, tmohare@usgs.gov, 813.884.9336x102; Kathi Hammett, khammett@usgs.gov, 813.884.9336x125; Yvonne Stoker, ystoker@usgs.gov, 813.884.9336x133

Other Supporting Organizations: Everglades National Park

Associated Projects: None

Overview & Status: The purpose of this study is to determine residual water flow and nutrient fluxes from the tidally affected reaches of the southwest Florida estuaries. Data collected at the five stations include water level, water velocity, specific conductance and temperature, total and dissolved nitrogen and phosphorus species, pH, and dissolved oxygen. Three stations were established in January 1997 (Broad, Harney, and Shark Rivers), and two additional stations were established in April 1999 (Lostman's Creek and North River. The Lostman's Creek and the North River stations also have been equipped with wind speed and direction sensors and barometric pressure sensors to correlate with water level and stream discharge. Stations are visited on a four to six week schedule for data retrieval, calibration of in-situ instrumentation, water sample collection, and discharge measurements. Water-quality data are collected using a modified equal-width-increment method. Samples from three sites across the river at each station are collected to obtain a depth-integrated and horizontally-integrated water sample. A multi-parameter water-quality meter is used to collect dissolved oxygen, pH, temperature, and specific conductance data. Discharge measurements are made using an acoustic Doppler velocity profiler. The Broad, Harney, and Shark Rivers nutrient data show significant relations between concentrations and specific conductance. The dissolved nitrogen concentrations are inversely related with specific conductance), and may indicate that the majority of dissolved nitrogen is transported from the up-gradient areas to the estuarine rivers as fresher water flows into these streams. Total and dissolved phosphorus concentrations for all three rivers are directly related with specific conductance and may indicate that the rivers are receiving higher concentrations of phosphorus from the Gulf of Mexico than from up-gradient areas. Data from the 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 also have been published to help disseminate the information generated by this study.

Needs & Products: This study provides information about residual water flow and nutrient flux from the southwest coast of Everglades National Park (ENP) to the Gulf of Mexico. The information from this study is used to assist in determining 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 and the Gulf of Mexico, calibration of hydrologic models of the south Florida mainland, and water-budget determinations for south Florida. Hydrodynamic models and computations are substantially more dependable and reliable because of the availability of water flow and nutrient flux data from this study. 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.

Application to Everglades Restoration: This study provides data for calibrating and validating hydrologic models, information on longer-term trends during the Everglades restoration and to provide