U.S. Department of the Interior
U.S. Geological Survey
WRI 87-4142

Rainfall and water-- quality data bases from the South Florida Water Management District were used to evaluate water-- quality trends at 10 locations near or in Water Conservation Area 3A in The Everglades. The Seasonal Kendall test was applied to specific conductance, orthophosphate- phosphorus, nitrate--nitrogen, total Kjeldahl nitrogen, and total nitrogen regression residuals for the period of 1978--82. Residuals of orythophosphate and nitrate quadratic models, based on antecedent 7-- day rainfall at inflow gate S--11B, were the only two constituent--structure pairs that showed apparent significant (p less than 0. 05) increases in constituent concentrations. Elimanation of regression models with distinct residual patterns and data outliers resulted in 17 statistically significant station-water quality combinations for trend analysis. No water-quality trends were observed.

The 1979 Memorandum of Agreement outlining the water-quality monitoring program between the Everglades National Park and the U.S. Army Corps of Engineers stressed collection four times a year at three stations and extensive coverage of water-quality properties. Trend analysis and other rigorous statistical evaluation programs are better suited to data monitoring programs that include more frequent sampling and that are organized in a water-quality data-- management system. Pronounced areal differences in water quality suggest that a water-quality monitoring system for Shark River Slough in Everglades National Park include collection locations near the source of inflow to Water Conservation Area 3A.

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