According to this report in the Miami Herald, the Army Corps of Engineers is going to begin lowering water levels in Lake Okeechobee next week. You can see why at one of my favorite blogs, the South Florida Watershed Journal: the lake has gone from under 11 feet (where it was for nearly 2 years) to over 14 feet in little more than a week, courtesy of Tropical Storm Fay.

For those of you who know the lake, our position has always been that lake levels should be about 13 feet in the dry season, with a maximum of 15 feet in the wet season (see AoF’s comments on the corps’ Lake O water regulation study of 2006); any more than that, and the littoral zone disappears, habitat diminishes, and, at higher levels, the levee starts to feel the strain. In fact, one prescription had a preferred schedule called “12 feet for 12 weeks” in two successive years.

But, back to the present. Here is how Curtis Martin describes our current situation in the Herald:

Suddenly, the question is no longer how low Lake Okeechobee will go, but how high.

The Army Corps of Engineers said Wednesday it intends next week to start slowly draining water as a precaution to protect the lake’s vulnerable and aging levee.

The big lake continued on a record rise and was on pace to hit 14 feet Thursday or Friday — only inches below its historic average and still three feet short of the danger zone where risk of levee leaks, erosion and potentially catastrophic breaches sharply rise.

But the Corps predicts the vast lake could continue climbing for at least another week to nearly 15 feet above sea level. And another storm could quickly raise the risks of levee failure and flooding across the rest of saturated South Florida.

”We’re still not at the peak of hurricane season,” said John Zediak, chief of the water management section for the Corps’ Jacksonville district.

The rise in Lake Okeechobee, the heart of a water supply system for five million people in South Florida, has been stunning — the fastest one-week climb in 77 years of record-keeping. Water levels in the lake, locked in historic lows for nearly two years, have shot up more than 2.5 feet in the week since Tropical Storm Fay struck near Marco Island, shattering a climb of 1.7 feet in 1951.

”The lake rise we have seen with this storm is something we have never recorded before,” said George Horne, deputy executive director for operations and maintenance for the South Florida Water Management District.

While inflows from the Kissimmee River basin to the north have slowed, Horne said, “There is still a lot of rain out there. Along the Kissimmee, there is ponding everywhere you look in fields and along roads.”

Miami-Dade and Broward are in ”decent shape,” Horne said, but it could take weeks for much of the rest of the district, which covers a region as far north as Orlando, to absorb Fay’s runoff.

And with water conservation areas of the Everglades and storm water treatment areas also running high, there simply isn’t any place to pump potential flood waters, he said.

In fact, Lake Okeechobee’s two main relief valves — the Caloosahatchee River to the west and the St. Lucie canal to the east — are still too swollen with local storm runoff to release lake water without flooding communities downstream.

After the 2004 and 2005 hurricane seasons, massive dumps of lake water polluted by farm and pasture runoff spawned algae and ravaged estuaries on both coasts, enraging environmentalists, fishermen and waterfront homeowners. The move backfired in 2006 when the Corps lower the still-rising lake in advance of a busy hurricane season that proved a dud — a decision that exacerbated the subsequent two-year drought and dropped the lake to an all-time low of 8.82 feet in July 2007.

For now, the Corps is planning only tiny releases — intended only to slow the lake’s rapid rise and keep it within a new normal seasonal range that drops to 12.5 feet during the dry season and rises to 15.5 feet at the peak of the wet season.

The new plan, adopted in April, reduces the lake’s peak storage by about a foot but gives the Corps more flexibility to balance water supply, environmental and public safety issues, Zediak said.

”It’s like being able to slowly drain a tub of water instead of just dumping a tub of water,” he said. “We kind of bleed it down. We’re better able to manage the lake.”

For those of you who are interested, here are some of the reasons we don’t want to send gobs of fresh (or nutrient-laden) water out to tide, taken from AoF’s comments of 2006:

To prevent the lake from exceeding 17.25 feet, the lake must be maintained considerably below the maximum desired level to be able to absorb storm-related runoff, which recent experience has shown can raise the lake by two feet (or more) from a single event. Thus, the preferred alternative has triggers to make significantly harmful releases to the estuaries when Lake Okeechobee is in the 15-foot range.  Levels in the 15-foot range are not harmful to the lake’s habitats. The planned maximum releases also are larger than previous schedules due to the urgency of keeping the lake low, and will create potentially larger plumes of fresh water that can affect larger areas of the estuaries.

UPDATE: Here is a link, which I should have included earlier, to Audubon of Florida’s position page on Lake Okeechobee.