Each bay receives an evaluation for the previous calendar year based upon the sampling values for three important indicators: chlorophyll a, nitrogen, and phosphorus. These measures of water quality were chosen because nutrient pollution is such an important focus of water resource management, especially where wastewater discharges or runoff from urban or agricultural areas is a concern. The Bay Conditions Report provides detailed information about these three primary water quality indicators, as well as other important measures of ecosystem health.
The rating for each bay is determined by the most recent sample values for these indicators, as compared to target and threshold levels defined for the individual bay. A threshold is an undesirable concentration which should not be exceeded; by contrast, a target is a desired level which, if achieved, should produce optimal seagrass growth and a productive coastal ecosystem.
The rating system used here was established by a team of local water resource management professionals and is based on work done by Janicki Environmental Inc. for the Sarasota Bay Estuary Program (SBEP) and the Coastal & Heartland National Estuary Partnership (CHNEP), to establish benchmarks for numeric nutrient criteria as required by the U.S. Environmental Protection Agency’s enforcement of the Clean Water Act. The criteria (thresholds) thus developed are now part of Florida Law. These rules may be updated over time; the current standards may be found in Florida Administrative Code, Chapter 62-302.530, “Table: Surface Water Quality Criteria”.
Specific goals defined in the scope of work for this project directed that the benchmarks established be:
- objectively defined
- scientifically defensible
- geographically specific
- related to a valued natural resource
- linked to a human activity that can be managed
The benchmark-setting strategy used by Janicki Environmental involved applying numerical analysis and models to a wealth of empirical data collected within Sarasota County's estuarine waters, including data on watershed characteristics, water chemistry, clarity, seagrass, and bathymetry.
For more information on the development of the targets and thresholds used here, read “Numeric Nutrient Criteria
Recommendations for the Sarasota Bay Estuary Program” (Mar. 2011) and “Proposed Numeric Nutrient Criteria for the Charlotte Harbor National Estuary Program Estuarine System” (Sept. 2011) prepared for the SBEP and CHNEP, respectively, by Janicki Environmental, Inc.