Everglades Agricultural Area Achieves 18 Percent Phosphorus Reduction, Agency Reports

Despite back-to-back hurricanes in 2004 and 2005 and an 18-month record regional water shortage, the South Florida Water Management District (SFWMD) confirmed on Sept. 13 that agricultural operations achieved an 18-percent reduction in the amount of phosphorus leaving the Everglades Agricultural Area for the 2007 water year.

Best management practices (BMPs) by farmers prevented 32 metric tons of phosphorus from entering the regional canal system, which sends water into the Everglades, during the monitoring period from May 1, 2006, to April 30, 2007. Over the past 12 years, the BMP program kept 1,767 metric tons of phosphorus out of the Everglades.

In cooperation with the South Florida Water Management District, local landowners are implementing the BMP program in the Everglades Agricultural Area, the 500,000-acre farming region south of Lake Okeechobee. BMPs are improvements in farming methods with the goal of enhancing water quality and reducing environmental harm. The most commonly used BMPs are improved fertilizer application, improved stormwater pumping practices and erosion controls to prevent phosphorus runoff.

A life-essential nutrient, phosphorus is a common ingredient in fertilizer and in the Everglades Agricultural Area's muck soils. When carried in stormwater runoff, however, excess phosphorus can impact the Everglades ecosystem to the south.

The BMP program mandated by Florida's Everglades Forever Act (EFA) stipulates that the amount of phosphorus leaving the Everglades Agricultural Area must be reduced by 25 percent in at least one year out of each consecutive three-year period. Although this water year's reduction is lower than the annual requirement, the EAA remains in compliance with the EFA, having achieved annual reductions ranging from 34 percent to 73 percent in each of the previous 11 years. An average phosphorus load reduction of more than 40 percent was achieved for the most recent three-year period from 2005 to 2007. The average reduction from the implementation of BMPs over the program's 12-year history is 50 percent, twice the amount required by law.

"South Florida's growers have worked cooperatively to implement sound, environmentally responsible farming practices that have set the standard for the rest of the state," said Eric Buermann, SFWMD governing board chairman. "Reducing phosphorus loads is critical to protecting and restoring America's Everglades. We are determined to continue the work to help farmers meet and exceed the target reduction next year and continue to improve and better protect our natural environment."

Together with best farming practices, water leaving the Everglades Agricultural Area receives additional treatment in one of several stormwater treatment areas (STAs) before entering the Everglades. These constructed wetlands are filled with native vegetation and use "green" technology to further reduce phosphorus levels. The District converted more than 41,000 acres of land south of Lake Okeechobee to STAs, and will add another 18,000 acres of treatment by 2010. STA expansion is part of the state's Acceler8 initiative to expedite critical restoration projects, providing for environmental benefits as soon as possible. Details of these projects are available at http://www.evergladesnow.org.

The results from water year 2007, which included the height of the 2006-2007 drought, show less phosphorus was removed over this monitoring period than in previous periods. Water managers believe sediments released from the bottom of Lake Okeechobee during the two active hurricane seasons of 2004 and 2005, followed by lower-than-normal water levels during the drought of 2006-2007, likely contributed to increased concentrations of phosphorus and other nutrients in water flowing from the lake to the Everglades Agricultural Area for irrigation. Absent these extreme conditions, continued implementation of BMPs is expected to yield higher phosphorus reductions in future non-drought years.

For more information, contact SFWMD at www.sfwmd.gov.

This article originally appeared in the 09/01/2007 issue of Environmental Protection.