WEST PALM BEACH — Lake Okeechobee is rising slowly at a rate beneficial for the Big O. According to biologists, a slow but steady rise allows the submerged aquatic vegetation to grow. If the lake rises too fast, it can damage SAV. On Thursday, the lake level was 13.4 feet above sea level.

In an Aug. 6 media teleconference, Lt. Col Todd Polk of the U.S. Army Corps of Engineers said Tropical Storm Isaias had little effect on lake, which only receive about three-quarters of an inch of rainfall.

He said the corps “buttoned up” the water control structures on the Herbert Hoover Dike before the storm, which included shutting the gates at Moore Haven and Port Mayaca on July 31 as the storm approached. With the Port Mayaca gate shut, as water level rose in the C-44 Canal (St. Lucie Canal) from local basin runoff, excess water was released through the St. Lucie Lock (S-80) into the St. Lucie River. On Aug. 2, flow through the St. Lucie Lock was 335 cfs. According to the corps report, for the seven-day period from July 31 to Aug. 6, flow at the St. Lucie Lock averaged 108 cubic feet per second, which equals about 400 million gallons of water for the period.

Heavy rainfall in the C-44 basin on Wednesday raised the water level in the canal from 13.7 feet to 14.72 feet on Thursday.

Lt. Col. Polk said the Port Mayaca gate was reopened to allow backflow into Lake Okeechobee, lowering the canal back to 14.5 feet, which is the optimal level for navigation in that canal. He said when the lake reaches 14 to 14.5 feet, water will no longer backflow into the lake because it is gravity flow. The canal will only backflow if the water level in the canal is higher than the lake level.

On the west side of Lake Okeechobee, no water has been released at Moore Haven. Lt. Col. Polk said there has been more than enough local basin runoff into the Caloosahatchee River to supply the freshwater flow needed for the estuaries. He said there are no plans to release water to the Caloosahatchee unless the flow of local basin runoff falls below the minimum 650 cfs level at the Franklin Lock. The Moore Haven lock will be closed for repairs Aug. 8-15, with intermittent closures on Aug. 8 and 9 and full closure Aug. 10-15.

He said satellite imagery shows there is algae bloom “potential” in about 25% of the lake. The most recent tests on the water samples indicate no toxins detected.

South of the lake, he said water is flowing as quickly as the water structures will allow to Everglades National Park, but water is still backed up north of the Tamiami Trail. He said all of the S-12 water control structures are open to allow flow under the Tamiami Trail. The corps data for Aug. 6 shows flow through the S-12s at 1,649 cfs. The water conservation areas (WCAs) south of the lake are above regulation schedule. No water can move out of WCA-1 or WCA-2 until the water level drops in WCA-3.