Lake Okeechobee levels are at dry season levels during the height of rainy season
Lake Okeechobee levels are low with only six weeks left in the rainy season, a scenario that could put sea grasses, oysters and marine critters that rely on the Caloosahatchee River estuary in trouble.
Summer is typically the time of year when Okeechobee releases blast down the channelized portion of the river, sending whitewater flows through the Franklin Lock and Dam in Alva.
But this year, lake levels are low at 12.6 feet above sea level, just above the lower end of the management spectrum. Those levels usually aren't seen until the late spring, well into the dry season.
"There's a lot of concern because September and October are kind of lottery months," said Paul Gray, a scientist with Audubon Florida. "(But) one tropical storm or hurricane can change things, so it's too soon to panic."
The U.S. Army Corps of Engineers is in charge of lake levels and tries to keep the surface of the lake between 12.5 and 15.5 feet above sea level to provide flood protection and water supply for agriculture, urbanized areas and ecological systems like the Caloosahatchee.
Historically, the Caloosahatchee River was not directly connected to Lake Okeechobee, but developers blasted a channel down the river decades ago to drain the Everglades for farming and development.
Nowadays too much rainwater runs off the landscape too quickly, and there's little left to feed the river's estuary during the drier months.
That's where the lake comes into play during dry times. It provides what the ditched-and-drained watershed can't.
Flows from the lake have been cut off in recent weeks, meaning that all the water flowing through the dam is coming from the eastern Caloosahatchee River watershed.
The dam is the cutoff point for the estuary, the separator between the fresh, upstream conditions and the brackish, downstream waters.
River advocates say the Army Corps has done a better job in recent years at providing the river with the needed water during dry times.
"What the Corps is trying to do is use their additional flexibility to hit a sweet spot," said Calusa Waterkeeper John Cassani. "If we get a hurricane and a lot of rain, that is going to fill the lake too fast; but if it stops raining and the lake stays low, there isn't enough water for water supply and for natural systems. They're walking the fence."
Army Corps spokesman Jim Yokum said there is a risk that less-than-average rain will fall north of Lake Okeechobee in the coming weeks and months.
"The forecast for the upcoming dry season indicates there is an increased risk of below normal rainfall due to a strong La Niña this winter," Yokum said. "Stronger La Niña conditions tend to mean less rain in the dry season."
Yokum said the idea is to keep water in the lake at this stage, not to conduct large releases.
"Holding that water in the lake right now when it isn’t needed can be helpful later in the dry season when it is more likely to be needed to meet the needs of water supply, including the needs of environmental water supply," he said.
Cassani said his group would like to see river flows around 750 cubic feet per second at the Franklin Lock and Dam. Ideally, the flows stay between that 750 and 2,800 cubic feet per second, the high-end harm threshold.
Rainfall on the upstream portion of the river's basin can force numbers higher than 2,800 cubic feet per second as measured at the dam.
The two sources, when combined, can wreak havoc on the estuary during large tropical storms and hurricanes. Water from the land and the lake are forced down the river, into the estuary and several miles out into the Gulf of Mexico.
"Right now, the rainfall in the local basin has been providing the Caloosahatchee River estuary with the freshwater it needs with very little support from the lake," Yokum said. "While we set a 457 (cubic feet per second goal), it has been getting significantly more than that this rainy season, and our periodic scientist calls and reports from partners and stakeholders indicate the salinity is in a very good spot right now."
Connect with this reporter: @ChadEugene on Twitter.