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J. N. “Ding” Darling National Wildlife Refuge - Greater Everglades Baseline Information and Response to CERP

Project Chief: Amanda C. Booth
Cooperator:Greater Everglades Priority Ecosystems Initiative (U.S. Geological Survey) and J. N. “Ding” Darling National Wildlife Refuge (U.S. Fish and Wildlife Service)
Period of Project:October 2010 – September 2014

Problem Statement

The Greater Everglades Ecosystem Restoration program (aka CERP - Comprehensive Everglades Restoration Plan) includes a management plan for the Caloosahatchee River that affects the quantity, quality, and timing of freshwater releases at Franklin Locks (S-79). The Caloosahatchee River receives freshwater from the natural watershed and a manmade connection to Lake Okeechobee. Above-average rainfall during the 2004 and 2005 hurricane seasons resulted in large freshwater outflows from the Caloosahatchee River and its tributaries to downstream estuaries, including the J. N. “Ding” Darling National Wildlife Refuge (DDNWR). Following these events, the refuge experienced an extensive algae bloom. Although the source of the bloom is not fully understood, it has been suggested that the large freshwater outflows from the Caloosahatchee River basin at S-79 contributed to the bloom.


  1. Provide basic information on water-quality trends at the mouth of McIntyre Creek, a key entry point to the DDNWR
  2. Determine relations between freshwater discharges from the Caloosahatchee River and potential degradation of environmental health inside DDNWR
  3. Delineate the spatial distribution of selected water-quality parameters along the tidal reach of the Caloosahatchee River and downstream estuaries


Data collection at the McIntyre Creek monitoring station include water level, discharge, salinity, temperature, dissolved oxygen (DO), pH, turbidity, chlorophyll, cyanobacteria, and colored dissolved organic matter (CDOM). Data is collected at 15-minute intervals.

Additionally, water-quality maps are produced on a quarterly basis and these encompass the tidal Caloosahatchee River, San Carlos Bay, Matlacha Pass, and Pine Island Sound. Using a flow-through onboard pump system, sensor and position data are recorded every 10 seconds as the boat travels at approximately 20 mph. Parameters recorded include salinity, temperature, dissolved oxygen, pH, turbidity, chlorophyll a, cyanobacteria and CDOM. Data are processed with an ESRI Arc Map GIS program to create contoured water-quality maps. These data provide information on the quality, quantity, and timing of water entering the DDNWR on a continuous basis.


As of March 2012, hydrologic data collected in this study are transmitted via GOES satellite every hour, stored in the USGS database, and can be accessed on a provisional basis via NWIS-web at Additionally, non-interpolated data for selected parameters are available as raw color-coded points overlaid on a map of the study area.

Preliminary results indicate:

  • Freshwater releases at S-79 precede salinity reductions in the tidal Caloosahatchee River and downstream estuaries.  Mean discharges at S-79 were 4,872 cfs in July 2010 and 211 cfs in January 2011; corresponding monthly mean salinities at McIntyre Creek were 25 and 32 ppt, respectively.
  • Dissolved oxygen concentrations in the Caloosahatchee River and neighboring estuaries reach hypoxic levels (<2 mg/L) intermittently.   The lowest dissolved oxygen concentration recorded at McIntyre Creek was 1.1 mg/L on June 17, 2010 and August 10, 2011.  Dissolved oxygen concentrations were <2 mg/L near S-79 on September 30, 2011. 

Information Products

Water Quality Monitoring at McIntyre Creek, J. N. “Ding” Darling National Wildlife Refuge, Presented at the Greater Everglades Ecosystem Restoration Conference, Naples, FL, July 12-16, 2010.

Water-Quality Mapping in the Caloosahatchee River, San Carlos Bay, Matlacha Pass, and Pine Island Sound, Florida, Presented at the National Water Monitoring Conference, Portland, Oregon, April 30-May 4, 2012.

Water-Quality Mapping and Monitoring Efforts in the Tidal Caloosahatchee River and Downstream Estuaries, Presented at INTECOL International Wetlands Conference, Orlando, FL, June 3-8, 2012.

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