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Drought helps South Florida growers meet water pollution goal

A drought that was bad for South Florida water supplies at least helped reduce the amount of damaging phosphorus that flowed off agricultural land and into the Everglades.

Pollution control measures, along with having less stormwater to clean up, enabled growers in the Everglades Agricultural Area to surpass the state standard for reducing phosphorus runoff that comes from fertilizer.

Growers in the more than 400,000-acre agricultural area south of Lake Okeechobee during the past year averaged 79 percent less phosphorous runoff than a state-set threshold allows, according to the South Florida Water Management District. The state standard calls for phosphorus runoff levels to be at least 25 percent below the threshold, which is based on levels before phosphorus reduction efforts began.

But environmentalists point out that the reduction is based on an average of phosphorus runoff from across the vast agricultural area, which helps hide the spots where pollution levels still far exceed state standards.

Also, just one tropical storm or hurricane could bring a rush of stormwater washing pollutants off farms and boosting phosphorus levels, warned long-time environmental advocate Rosa Durando.

"What has controlled it this year is a lack of rainfall," Durando said. "You still have a problem."

With or without the drought, agricultural advocates say their phosphorus reduction efforts are succeeding. They point out this is the 16th consecutive year meeting the state’s phosphorus reduction goal.

"It’s an example of the kind of success that can be achieved in partnership with scientists and farmers who roll up their sleeves to get the job done," said Barbara Miedema, vice president of the Sugar Cane Growers Cooperative of Florida.

An influx of phosphorus-laden stormwater washing off agricultural fields fuels the growth of cattails that crowds out other habitat vital to the Everglades ecosystem.

Phosphorus pollution starts on pastures and other agricultural fields north of Lake Okeechobee and gets washed into the lake that is relied on to irrigate South Florida sugar cane and other crops. Phosphorus and other pollutants that wash off those South Florida agricultural fields add to the water problems that eventually reach the Everglades.

Growers are required to take steps to lessen phosphorous runoff such as cleaning out drainage ditches, refining water pumping practices and lessening fertilizer use.

The runoff from those agricultural fields is then directed to the South Florida Water Management District’s more than 40,000 acres of stormwater treatment areas – man-made marshes with pollution absorbing plants that help remove phosphorous before the water makes its way the Everglades.

The problem is the cleanup efforts have yet to meet the ultimate goal of getting phosphorous levels in the water headed to the Everglades down to 10 parts per billion.

One solution is imposing more pollution cleanup requirements on South Florida growers to deal with more of the phosphorus before the water gets to the stormwater treatment areas, according to the environmental group Audubon of Florida.

The district’s enforcement of phosphorus requirements are "underfunded," with just five engineers to conduct inspections across the 600,000 acre area, according to Charles Lee of Audubon.

While growers are meeting state phosphorus reduction requirements based on a regional average, some farms still have phosphorus runoff levels that register 500 parts per billion, Lee said.

"There is significant room for improvement," Lee said.

Copyright © 2014, The Baltimore Sun
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