Lake Okeechobee discharges to St. Lucie River, Indian River Lagoon top 50 billion gallons

The 50 billionth gallon of Lake Okeechobee water in the current round of discharges poured through the St. Lucie Lock & Dam sometime Monday.

That's TCPalm's estimate based on the Army Corps of Engineers's daily discharge calculations since the releases began Sept. 15.

The 50 billion gallons of Lake O water has combined with much more rainwater runoff  from canals stretching into western Martin and St. Lucie counties to turn the St. Lucie River the color of chocolate milk.

The brown water extends through the southern Indian River Lagoon and in a plume spreading out the St. Lucie Inlet and several miles into the Atlantic Ocean.

As bad as the current round of discharges is, it doesn't come close to the amount of contaminated water dumped into the St. Lucie River and Indian River Lagoon from the top 12 discharge events, aka "The Dirty Dozen," including:

• 507 billion gallons: the largest recorded discharge event, from October 1969 to May 1970
• 237 billion gallons: the "guacamole" blue-green algae bloom caused by discharges from Jan. 30 to Nov. 4, 2016
• 136.4 billion gallons: the "Lost Summer" discharges from May 8 to Oct. 21, 2013
• 130.2 billion gallons: the 12th-highest discharge event from March-August 1969 that's still more than twice the current discharge total.

Lake Okeechobee discharging into St. Lucie River, Indian River Lagoon | Graphic

How long will they last?

"I don't see the releases stopping anytime soon," said John Campbell, spokesman for the Army Corps of Engineers.

When the current discharges will stop depends on how much more the lake level rises, and that depends on how more it rains north of the lake.

More: What you should know about brown water polluting our rivers, lagoon and beaches

A foot of rain in the Kissimmee River basin north of Lake O could add 3 feet of water to the lake.

Research by the National Weather Service in Melbourne shows the winter dry season on the Treasure Coast typically starts between Oct. 17 and Oct. 22.

"It's going to be late this year," meteorologist Derrick Weitlich said Monday. "There's nothing on the horizon that's going to bring about the start of the dry season. We've got a front moving through on Tuesday that will allow the temperatures to drop somewhat, but rain chances are still high through the week."

Lake O level

The Corps discharges water from the lake east to the St. Lucie River and west to the Caloosahatchee River to keep the lake elevation from reaching too high and threatening the surrounding Herbert Hoover Dike.

The Corps tries to keep the lake elevation below 15 feet 6 inches but only starts getting really concerned when the elevation tops 17 feet. The lake elevation has been as high as 18 feet 9 inches.

Lake O's elevation rose 3 feet in 30 days since early September and reached 17 feet 2½ inches Thursday. Since then has dropped a quarter of an inch to 17 feet 2¼ inches Monday morning.

"Even with maximum discharges, all we've done so far is slow the lake's rise," Campbell said. "We still haven't gotten the lake level to go down consistently, although the fact that it's gone down a little bit over the past few days may indicate that that downward trend is just around the corner."