Lake still suffering from Hurricane Irma damage

OKEECHOBEE — In other areas of the country, people pray for rain. Okeechobee fishermen are praying for a drought.

In September Hurricane Irma churned the waters of the Big Lake, ripped up aquatic vegetation and left the shoreline littered with uprooted plants. After the storm, drainage from the north caused the lake to rise rapidly, drowning the nearshore vegetation with high water.

The lake’s ecosystem recovery can’t start until the water recedes.

On Feb. 8, the Florida Fish and Wildlife Conservation Commission hosted a meeting at the South Florida Water Management District office in Okeechobee, to discuss aquatic plant management. It quickly became apparent that, due to the hurricane damage, there are few areas of aquatic plants left to manage.

Zach Welch, of the South Florida Water Management District Lake and River Ecosystems division, explained there are three parts of the lake in play. The Pelagic Zone is the deep water near the center. This is where the muck build up is, and it tends to be muddier than the other parts of the lake. The Nearshore Zone has clear or turbid water, depending on how high the lake is. The Littoral Zone (the marshes around the edge of the lake) has shallow water, dense vegetation and clearer water.

“In the Nearshore Z, higher lake stages tends to increase the ability for the turbid water to be transported into the grassline,” he said.

As the lake level increases, so does the phosphorus level in the Nearshore Zone, Mr. Welch explained.

Around 16 ft., there is not a lot of difference between the Nearshore Zone and the water in the lake center, he added.

With lower lake stages, more plants can grow in the Nearshore Zone.

“When the water is deep, it makes it harder for them to grow there,” he said.

The beneficial range for the lake level is about 12 ft. to about 15 ft to 15.5 ft., he said. The lake needs annual low water periods to allow the areas around the edge of the lake to dry out so that the vegetation can grow.

When the lake level recedes, the macro-algae responds first, he said. “Because it’s an algae, it responds quickly to good light conditions.” (This is a beneficial type of algae.) Vascular submerged plants such as eel grass, “they take a while to respond,” he said. “The low water condition is when they can produce seeds and sprout and start recovering.

“We’ve had a lot of years in a row we have been above that preferred range,” he continued.

“In 2016, it had two high water events and water level did not get down.”

“2013 was the year when we started going above the preferred range, and we don’t get down very low – only 13.5 ft.” he said.

“By 2016 the only submerged plants we had were inside the grass line,” Mr. Welch continued.

“In June we had low water conditions, just what we needed for the plants to grow – then Hurricane Irma hit.”

He said they surveyed the lake after the storm.

“We lost about 11,000 acres of submerged aquatic plants,” he explained.

“We are going to need low water again to recover these plants.”

During the hurricane, Irma’s winds pushed the water up higher than 20 feet at Fisheating Creek. At the same time, the east side of the lake dropped down below 10 feet.

“There was 11 feet of difference because the wind was blowing so hard,” he said. “You can imagine what that does, with the water sloshing around, stirring up the mud. That’s not good for the plants.”

The hurricane debris also created a barrier at the edge of the marsh, further disrupting the natural ecosystem.

“There are long term effects when we have this turbid water and high lake stages,” he said.
Newton Cook of United Waterfowlers Florida said he watched the same thing happen after the hurricanes of 2004 and 2005.

“During the hurricanes, lake was gone,” he said. “I watched people cry.

“The problem we had was the turbidity of the lake had gotten so bad and the muck on the bottom was in a colloidal suspension and it was not settling and it was not going to settle.

“We thought the lake was gone, and then we had a miracle. We had a drought. The lake got down to 10 feet,” he said.

“We got the lake back because of all that vegetation.

“Today we are right back in the soup because the lake has been held too high. There are reasons why the Corps (U.S. Army Corps of Engineers) holds the lake high. The biggest reason is they can’t send the water anywhere except the estuaries.

Mr. Cook said that while after the hurricane water from the north was rushing into Lake Okeechobee at 30,000 cubic feet per second, no water could be sent south to the Everglades because the waterways were closed to protect the habitat of the Cape Sable Sea Sparrow.

Even if the waterways had been open, he said, flow into Everglades National Park is restricted by the Tamiami Trail, which was built to connect Tampa and Miami. The road acts as a dam, stopping the natural sheetflow of water.

“When you’ve got 30,000 cfs coming in from the top, the lake is going to be too high,” he said.

“If you go to church, pray for a drought,” Mr. Cook advised.

Mr. Cook added that he understands the need for chemical controls for the non-native invasive plants such as water lettuce and water hyacinth.

If you don’t spray those plants, within 6 months the mats of vegetation will grow to the point that you could walk across the lake, he said.

“I’ve been stomping this lake since 1985,” said Jeff Seeger. “I’ve been watching it die since 1985.”

He said the lake used to have a sand bottom, but the changes in the drainage and flow have caused it to build up muck in the lake center.

The Tamiami Trail is a significant block to the flow, he said. “We need to double that flow.

He said the Cape Sable Sea Sparrow “might need to be put on a side burner to the efforts to save the Everglades and Biscyane Bay.

“Everything depends on the southerly flow that we are deprived of from Lake Okeechobee,” he said. “In the meantime, the salinity of Florida Bay has been rising.

“Lake Okeechobee does not exist in a bubble,” he said.

Editor’s note: According to SFWMD, the maximum flow under the Tamiami Trail with current water control structures is 8,000 to 10,000 cfs. However, no flow was allowed following Hurricane Irma. Since the Water Conservation Areas south of the lake were already full and no flow was allowed out of the WCAs to Everglades National Park, the only flow allowed from the lake was east and west to the coastal estuaries.

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