The biggest public toilet flushing in the country is underway at Lake Okeechobee.

To lower water levels, the U.S. Army Corps of Engineers is dumping billions of gallons into inland waterways that empty into the Atlantic Ocean and Gulf of Mexico. Loaded with nutrients and farm chemicals, the torrent is deadly for shrimp, oysters, grass beds, fish and near-shore reefs.

Viewed from the air, the brown stain pouring into the ocean from the St. Lucie Inlet is unmistakable for what it is: a gusher of pollution.

And nobody will stop it.

The Corps is in charge of maintaining Lake Okeechobee, ringed by an old dike that needs constant upgrading. It exists not only to protect surrounding communities from flooding, but also to hold fresh water for farmers, ranchers and South Florida suburbs.

In reality, the lake is managed primarily for Big Agriculture. One reason its dirty overflow isn’t pumped south is because it would soak the sugar fields.

And, as Floridians well know, the sugar companies have more political clout than the shrimpers, commercial fishermen or regular folks who live along the waterways and now get to watch the crud churning past their docks.

Every so often, when the rainfall gets exceptionally heavy, the Army Corps opens the floodgates at Lake O and sends all that crappy lake water to the coasts.

For catheters they use the Caloosahatchee River, which runs west toward the Gulf of Mexico, and the St. Lucie Canal, which heads east toward the ocean through a prime estuary.

“It’s really a mess. Very destructive,” said Mark Perry, executive director of the Florida Oceanographic Society.

This year, the trouble started with slow-moving Tropical Storm Isaac and worsened with continued heavier-than-usual rains. The level in Lake O kept rising, and the Army Corps on Sept 19. began “releasing” 581 million gallons of water per day.

Last week, the amount of dumping surged to 1.2 billion gallons a day. The lake is silted with fertilizers, nitrogen and other agricultural spillage that stirs whenever the gates are opened.

Enough polluted muck to fill 12 dump trucks is entering the St. Lucie Estuary every day. If a factory was polluting so flagrantly, it would have been shut down a long time ago.

But, see, it’s the government.

Given a choice between drenching some cane and devastating a marine habitat, the Corps remains bound by this administration (like past administrations) to favor the sugar companies and other growers south of the lake.

According to Perry, healthy salinity levels in the St. Lucie Estuary are 20 to 24 parts per thousand. Recent tests at the Roosevelt Bridge in Stuart have shown salt levels below 5 parts per thousand. Oysters are dying and the sea grasses are in jeopardy, he said.

Algae blooms will be next. The last time that happened, a miles-long river of green slime appeared, and fish kills followed.

Every rainy season, water managers at Lake O hover near their pump handles in dread of what might come. Two years ago they emptied 300 billion gallons in anticipation of flooding. The rains didn’t materialize, a drought took hold and by 2011 parts of the lake bottom went bone-dry.

The Corps knows the damage that unleashing so much water causes, but its options are few. So far, the big flush of 2012 isn’t as humongous as the panicky dumpings of 2004 and 2005, which created a putrid mess and a public uproar. Sen. Bill Nelson and a few others stepped forward, but not much changed. The Everglades restoration project, a joint state-federal effort, still hasn’t advanced far enough to ease the Okeechobee problem.

Long ago, before South Florida was re-plumbed, the lake drained naturally into the filtering Everglades. The engineering exists to make that possible again, without swamping subdivisions and closing down sugar production.

Send the water south slowly, cleansed along the way by retention ponds, and it will feed the Aquifer upon which millions of Floridians depend. Instead we’re still pumping straight to the oceans, killing marine life and crippling small businesses that depend on a thriving waterfront environment.

The wastefulness is idiotic, the destruction criminal, and the silence from Washington is nauseating.

As the drainage canals leading south from Okeechobee remain closed, in deference to Big Sugar, a continual deluge of waste water is destined for our coasts. And the lake’s still too high.