The Caloosahatchee oxbows are sections of the old river which remained after channelization and creation of C-43. Thirty-five of these small, isolated river sections are located between the W.P. Franklin Lock and the city of LaBelle. The oxbows are important to the rivers ecosystem because their relative isolation results in tranquil conditions more conducive to wildlife habitat than the main C-43 channel. The main C-43 channel is characterized by a deep, scoured channel (25 feet) and a eroded dredge-material shoreline -- the result of heavy boat traffic (the Caloosahatchee is part of the Intercoastal Waterway.) The oxbows are shallow (less than 6 feet deep) and typically have undeveloped islands and shorelines of a more natural character. In addition to their wildlife habitat value, the oxbows also serve a cultural and aesthetic function since they represent the only remaining portions of the original Caloosahatchee River.

Nutrient, chlorophyll a and other water quality parameters were measured in 1978 by James Milleson of SFWMD in six "open" oxbows and one "closed" oxbow along the Caloosahatchee. An open oxbow is one in which both ends are connected to the main river channel while in a closed oxbow, only one end of the oxbow has a hydraulic connection to the main channel. When data for the six oxbows of similar configuration are compared, nitrate concentration shows a correlation (r=0.87) with the chlorophyll concentrations (Table 1). Both ortho-phosphorus concentration (r=0.47) and total phosphorus concentration (r=0.12) show much lower correlation with chlorophyll. In almost all cases, phosphorus concentrations were relatively uniform while nitrate showed some variability over the six oxbow sites. Further study is justified given the very limited water quality data available for the Caloosahatchee oxbows.

Task 1. SOP, and site report.

Deliverable 1 (SOP and site report) will developed following collection of the first set of water samples from the oxbows. The initial sampling trip will serve as a shake-down cruise to refine specific sampling points, sampling methodology, sample handling techniques, sample labeling systems, and boat handling methods. The report will be submitted two weeks after the IFAS project release date for this contract.

The (SOP) standard operating procedure will serve as the governing QA/QC document for the project. It will include FDEP Comprehensive Quality Assurance Plan (CompQAP) for the participating labs (the IFAS Southwest Florida Research Laboratory – IFAS SWFRL and the Lee County Environmental Laboratory – LCEL) and a Quality Assurance Project Plan (QAPP). All procedures and equipment used on the sampling trips will be described in the SOP, CompQAP, and QAPP.

Ten of 35 oxbows located between Franklin Lock and LaBelle (see Figure 1) have been selected as the sampling sites. These oxbows identification numbers are: 2, 3, 9, 11, 13, 15, 18, 24, and 32. The site report will document exact sampling locations for each oxbow using GPS and describe local site characteristics that may influence water quality conditions. The GPS unit will be made available to IFAS by SFWMD for use in this project.

Task 2. Sampling.

Deliverable 2 will consist of a final report documenting delivery of the sample sets delivered to LCEL by IFAS. To ensure compatibility with LCEL methods and procedures, preparation of sample containers will be the responsibility of LCEL. The IFAS employee will pick up fresh sets of sample containers, filter assemblies, and other sampling consumables from LCEL at the time of each delivery of oxbow water samples to LCEL. Invoices for task 2 will be submitted to CES along with a final report including copies of signed chain of custody forms documenting delivery of samples by IFAS to LCEL

Samples will be taken at the upstream and downstream entrances to the oxbows at a depth of 30 cm from the water surface. Sampling of the ten oxbows sampled in three episodes. Sample acquisition, processing and storage methods will be consistent with requirements for analysis of NOx, total P, Ortho P, turbidity, color, Hg, Pb, chlorophyll a, ultimate BOD, fecal coliform bacteria, and fecal streptococcus. In addition to preprocessing on ship board for chlorophyll a, SWFRL personnel will measure a profile of temperature, pH, conductivity, and DO.

Copies of analytical results will be provided by LCEL and CES to IFAS on a monthly basis. Publications based on the results of this project will include participating investigators as co-authors.