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For a complete view of Southern Florida data and for additional information about specific benchmarks used, visit our Web site at Also visit the NAWQA Data Warehouse for access to NAWQA data sets at

This appendix is a summary of chemical concentrations and biological indicators assessed in Southern Florida. Selected results for this Study Unit are graphically compared to results from as many as 36 NAWQA Study Units investigated from 1991 to 1998 and to national water-quality benchmarks for human health, aquatic life, or fish-eating wildlife. The chemical and biological indicators shown were selected on the basis of frequent detection, detection at concentrations above a national benchmark, or regulatory or scientific importance. The graphs illustrate how conditions associated with each land use sampled in Southern Florida compare to results from across the Nation, and how conditions compare among the several land uses. Graphs for chemicals show only detected concentrations and, thus, care must be taken to evaluate detection frequencies in addition to concentrations when comparing study-unit and national results. For example, norflurazon concentrations in Southern Florida ground water in agricultural areas were similar to the national distribution, but the detection frequency was much higher (72 percent compared to 2 percent), and Graph showing Pesticides in water—Herbicides and CHEMICALS IN WATER Concentrations and detection frequencies, Southern Florida, 1996–98—Detection sensitivity varies among chemicals and, thus, frequencies are not directly comparable among chemicals


Graph showing Pesticides in water—Insecticides and Volatile organic compounds (VOCs) in ground water


Graph showing Nutrients in water and Dissolved solids in water


Graph showing CHEMICALS IN FISH TISSUE AND BED SEDIMENT Concentrations and detection frequencies, Southern Florida, 1996–98—Detection sensitivity varies among chemicals and, thus, frequencies are not directly comparable among chemicals. Study-unit frequencies of detection are based on small sample sizes; the applicable sample size is specified in each graph.


Graph showing Organochlorines in fish tissue (whole body) and bed sediment


Graph showing Semivolatile organic compounds (SVOCs) in bed sediment and Trace elements in fish tissue (livers) and bed sediment and BIOLOGICAL INDICATORS Higher national scores suggest habitat disturbance, water-quality degradation, or naturally harsh conditions. The status of algae, invertebrates (insects, worms, and clams), and fish provide a record of water-quality and stream conditions that water-chemistry indicators may not reveal. Algal status focuses on the changes in the percentage of certain algae in response to increasing siltation, and it often correlates with higher nutrient concentrations in some regions. Invertebrate status averages 11 metrics that summarize changes in richness, tolerance, trophic conditions, and dominance associated with water-quality degradation. Fish status sums the scores of four fish metrics (percent tolerant, omnivorous, non-native individuals, and percent individuals with external anomalies) that increase in association with water-quality degradation.


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U.S. Geological Survey Circular 1207

Suggested citation:

McPherson, B.F., Miller, R.L., Haag, K.H., and Bradner, Anne, 2000, Water Quality in Southern Florida Florida,1996–98: U.S. Geological Survey Circular 1207, 32 p., on-line at

U.S. Department of the Interior, U.S. Geological Survey
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