For the first time in more than two years, the Army Corps of Engineers this morning allowed polluted stormwater from Florida's Lake Okeechobee to pour into the Caloosahatchee and St. Lucie rivers, where dangerously high spikes in nitrogen and phosphorus are likely.

The planned 11 days of water "pulses" are intended to ease pressure on the south Florida lake's fragile earthen dike, which is undergoing repairs and reinforcements to protect communities and sugar fields immediately south of the lake.

In a public notice, the corps' Jacksonville District office said water releases would amount to 4,000 cubic feet per second down the Caloosahatchee, which drains to the Gulf of Mexico near Fort Myers, and roughly half that amount down the St. Lucie River, which drains to the Indian River Lagoon and the Atlantic Ocean near Stuart.

While the corps maintains that its pulses of Lake Okeechobee water are designed "to mimic nature and provide discharges ... similar to what might be seen during a typical rainfall event," environmentalists have strongly criticized the practice, saying it poses major threats to the receiving estuaries.

They say one possible solution is for the state to finalize its planned purchase of nearly 200,000 acres of farmland south of the lake from U.S. Sugar Corp. The deal would allow the corps to store excess water in new treatment reservoirs rather than dumping it in the rivers.

As recently as 2005, the St. Lucie estuary experienced an explosion of toxic blue-green algae linked to polluted Lake Okeechobee discharge, resulting in fish kills and public health advisories discouraging direct contact with water in the Indian River Lagoon.

"We have fish with lesions almost every time we have major discharges," Mark Perry, executive director of the Florida Oceanographic Society and state co-chairman of the Everglades Foundation, said in a conference call with reporters this morning. "It gets the water out of the lake, but it has devastating effect" on the downstream estuaries, he said.

Other species habitats, including oyster beds and sea grasses that provide vital fish nurseries, also are harmed when the estuaries experience rapid changes in salinity due to shocks of freshwater from the lake, he added.

Before today's releases, no water had been discharged from Lake Okeechobee since 2006 because the region was experiencing a prolonged drought. As recently as this spring, wildfires were burning across the exposed lake bottom, where years of organic matter had accumulated and dried into tinder.

But last month's Tropical Storm Fay dumped more than 25 inches of rain across portions of Florida, including Lake Okeechobee's primary feeder watershed, the Kissimmee River, which drains much of central Florida south of Orlando.

Paul Gray, the Audubon Society's chief scientist on Lake Okeechobee, noted that the lake remains the only catch basin for stormwater draining from central Florida, and that it is consistently overtaxed by even moderate flood events.

Since Fay's slow pass across the state in mid-August, stormwater runoff has raised the lake's level by 40 inches, from 11.3 feet on Aug. 15 to nearly 15 feet today. Given the projected path of three westward-moving tropical systems -- Hanna, Ike and Josephine -- Gray said the lake "is literally one storm away from being in big trouble."

'This doesn't work for anybody'

Environmental groups say the lake's chronic water problems could be solved, however, with the completion of the state's proposed $1.7 billion U.S. Sugar acquisition, announced by Gov. Charlie Crist (R) in June.

That deal would involve the conversion of more than 185,000 acres of sugarcane fields into storage basins that would allow water managers to treat and then release billions of gallons annually to the parched lower Everglades. Excess water also could be set aside for use by farmers and water utilities during drought periods like the one that just ended, Gray said.

"Two months ago, we were in severe water rationing mode; now we're about to start dumping vital water again," Gray said. "This doesn't work for anybody."

Leon Abood, former president of the Realtor Association of Martin County and chairman of the Rivers Coalition, which organized in 1998 to oppose the corps' releases from Lake Okeechobee, said the U.S. Sugar land deal, more than simply aiding Everglades restoration, will help secure the tourism- and service-based economies on both coasts by protecting their most important resource, clean water.

"This event should galvanize the citizens of Florida to support Gov. Crist's proactive attempt to acquire these lands," Abood said. "It's good for Lake Okeechobee, it's good for the Everglades, and it's good for updating an 80-year-old water supply system."