An old source of Lake Okeechobee pollution could return after South Florida water managers Thursday opened the door to renewed "back-pumping."

In a bid to boost water supplies, the South Florida Water Management District board agreed to explore pumping some of the polluted stormwater that drains off South Florida farmland back north into Lake Okeechobee for storage.

The district stopped that controversial practice five years ago because of environmental concerns about sending water containing polluting phosphorus as well as pesticides into the lake.

Environmental groups are up in arms about an amendment to a transportation bill passed through the House of Representatives on Wednesday that would prevent the EPA from regulating coal ash and its byproducts on a federal level.

Also known as coal combustion residuals (CCR), coal ash is a byproduct of large-scale coal-burning from coal-based power plants. The 14 coal-burning power plants in Florida, the closest to Tampa being the Big Bend Power Station in Apollo Beach, generate about a quarter or the state’s electricity and about 8 billion pounds of coal ash a year. There is currently no federal regulation on the disposal and storage of coal ash.

Two years ago this week, the U.S. Environmental Protection Agency proposed federal standards for coal ash, the byproduct of burning coal. That proposal never went anywhere.

Yesterday—two years to the day from the EPA proposals—the U.S. House of Representatives voted to instruct the Transportation Conference Committee to keep language in the highway bill that would block the EPA from designating coal ash as hazardous waste. The language—in the form of an amendment by West Virginia Republican Rep. David McKinley—is included in the House’s Surface and Transportation Extension Act of 2012.