Pump Stations Deliver Dirty Water to the Everglades

The Numeric Phosphorus Criterion

Research by the South Florida Water Management District and the Florida Department of Environmental Regulation strongly validates the original decision of the Legislature to select 10 parts per billion as a "default standard" for the Everglades. Research submitted to DEP by unbiased sources documents that normal background concentrations of phosphorus in healthy Everglades sawgrass marshes and sloughs hover in the range of 6 - 8 parts per billion.

In order to cross-check the proper numeric concentration, DEP and SFWMD researchers established transects which run through both impacted Everglades wetlands (those areas already damaged by phosphorus) and out into pristine areas. By measuring the phosphorus levels, and comparing them to a distance scale, researchers then were able to correlate the level of phosphorus with locations where healthy Everglades marshes switch to impacted areas with unfavorable vegetation changes. Those measurements documented that shifts in vegetation, both in large plants such as sawgrass and in communities of microorganisms, such as periphyton, began to take place as phosphorus levels crossed the 10 part per billion threshold.

Other experiments were conducted by "dosing" otherwise healthy plots of Everglades vegetation with different levels of phosphorus, and comparing the results with "control" sites at the same location that are not "dosed". These tests also demonstrated conclusively that once phosphorus levels rise past 10 parts per billion, imbalances in the Everglades vegetation begin to appear.