The U.S. Army Corps of Engineers is releasing water east to the St. Lucie River at 500 cubic feet per second and west to the Caloosahatchee at 2,000 cfs. How much difference will that make in the level of Lake Okeechobee?

• 500 cfs equals 323.15 million gallons per day or 2.2 billion gallons per week.

• 2,000 cfs equals 1.29 billion gallons per day or 8.84 billion gallons per week.

One inch on Lake Okeechobee is about 12 billion gallons of water.

The flow entering the estuaries is a mixture of lake water and local basin runoff. The Caloosahatchee flow is measured at the Franklin Lock – more than 40 miles from the Julian Keen Jr. Lock at Moore Haven, where Lake Okeechobee releases enter the Caloosahatchee River. The St. Lucie flow is measured at the St. Lucie Lock – more than 20 miles from Port Mayaca, where Lake Okeechobee releases enter the St. Lucie Canal.

Even if there is no rainfall that week and all the water released through the Franklin and St. Lucie Locks came from Lake Okeechobee, the releases equal less than 1 inch per week on Lake Okeechobee. With 17 weeks left before the start of the rainy season, the releases east and west would lower Lake O by about 15.6 inches.

At the same time, water continues to flow into the lake from the north. Water managers continue to release water from the Kissimmee Chain of Lakes into the Kissimmee River. The natural recession of the lakes during the dry season means those lakes will have capacity to hold more water when the wet season arrives.

Flow south is based on capacity. With the lake level high, water users south of the lake – both agricultural and urban – have as much water as they need. How much they need depends on rainfall.

Where did all this water come from?

Hurricane Ian dumped about 1 million acre feet of water in the watershed between Orlando/Kissimmee and Lake Okeechobee. The heaviest rainfall was in the urban areas at the top of the watershed. To protect human life, water managers moved that water south as quickly as possible, using massive pumps if necessary to move the water away from Orlando/Kissimmee.

In his Dec. 28, 2022 statement about the U.S. Army Corps of Engineers Dry Season Strategy, Col. James Booth, explained: “During the height of hurricane emergency response efforts, our decisions were easy to reduce immediate impacts. Now, the question of how to manage all the water in Lake Okeechobee is upon us, and the solution is not an easy one. The lake climbed 4 feet in two months. We finally saw the lake peak at 16.51 feet.”

The lake’s “ecological envelope” ranges from 12.5 feet to 15.5 feet. Levels above 15.5 feet are damaging because the water stacks up against the Herbert Hoover Dike, drowning out the marshes. If the water rises faster than the submerged aquatic vegetation (SAV) can grow, the SAV is damaged or destroyed. Lake levels of 12.5 feet or lower are needed for new SAV to sprout.

As of Jan. 30, the lake level was 16.02 feet.

Why can’t the lake water be sent south?

A big obstacle in sending water south is the quality of the lake water. Before water can be sent under the Tamiami Trail into Everglades National Park, under federal regulation it must be cleaned to no more than 10 parts per billion phosphorus. The water coming into the lake from the north is many times that level. Consecutive years of high lake levels have destroyed much of the SAV that acts as the lake’s filter system.

The stormwater treatment areas in the Everglades Agricultural Area were designed and built to treat wet season runoff from the EAA, which is lower in phosphorous than the lake water. Those STAs don’t have the capacity to treat large volumes of lake water. In addition, part of the capacity of the STAs is taken up by direct rainfall. Hurricane Ian and Hurricane Nicole brought heavy rainfall south of the lake. During the dry season, the STAs also need to dry out and recover from the high water levels from the wet season.