NAPLESNEWS
April 7, 2007

Caloosahatchee River has it backward - water flow, that is

By Julio Ochoa

http://www.naplesnews.com/news/2007/apr/07/caloosahatchee_river_has_it_backward_water_flow/

Part of the Caloosahatchee River is flowing backward. At least that’s what measurements taken by the U.S. Army Corps of Engineers show.

The reports, which show hundreds of millions of gallons from the headwaters of the Caloosahatchee flowing back into Lake Okeechobee, are very concerning, said Wayne Daltry, director of Smart Growth for Lee County. The water, which is likely being pumped back out of the lake for agricultural users, could help lower salinity levels in part of the county’s drinking water supply, Daltry said.

Instead, salinity levels have risen so high in the Olga Water Treatment Plant, which serves part of Fort Myers, the county had to issue warnings to its users. And salinity levels likely will keep going up because when water flows backward at the river’s headwaters, saltwater is sucked up through the river, Daltry said. “They are letting water go to the farmers but not requiring them to keep enough flowing so it gets to the water plant,” he said. “People’s drinking water is salty and getting saltier.”

Thursday, 18 cubic feet per second of water flowed into the lake. In previous days, hundreds of cubic feet per second flowed into the lake. That amounts to hundreds of millions of gallons of water, Daltry said. Lee County Utilities had to warn about 13,000 users who get water from the Olga plant when sodium levels reached 160 parts per million. A couple weeks ago, sodium levels in the plant’s water were 171 parts per million. By Monday, the levels had climbed to 197 parts per million.

Drinking a liter of water with 200 parts per million sodium is the same as eating 1/10th of a teaspoon of salt or eating 1/3 of a fast food cheeseburger. The high sodium levels aren’t dangerous to people unless they are on salt-restrictive diets.

However, if sodium levels reach 250 parts per million, people may start to taste it, said Gary Maier, an engineer for the Lee County Department of Health. “At some point, people won’t drink it because it’s going to taste like the ocean,” Maier said.

Still, the water will have a long way to go to reach the ocean’s salinity, which contains about 20,000 parts per million, he said. A series of gates and locks control the flow of water from Lake Okeechobee to the river. When the lake’s level drops below 10.5 feet — it’s currently at 10.2 feet — gravity no longer carries the water down river.

When the gate nearest to the river is opened, water can sometimes flow into the lake, said Andrew Geller, a hydraulic engineer in the water management section of the Army Corps of Engineers. But the difference between the lake’s level and the river’s level is so slight right now, water is barely flowing in either direction, Geller said. “If there is no difference between upstream and downstream, it’s hard to judge which way the water is moving,” he said.

If a strong wind blows from west to east when the gate is open, it could cause some reverse flow, Geller said. Even the Corps’ measurements could be suspect, he said, because the margin of error in the measurement instruments is plus or minus 400 cubic feet per second. The Corps is sending freshwater to the Caloosahatchee through another gate further downstream, Geller said.

But if the Corps kept the gate closest to the lake closed, more of the fresh water that flows into the river from the basin could reach the water plant, Daltry said. On the other side of the lake, gates that open into the St. Lucie river show no backflow of water. “Yes, the water is going backwards and it’s deliberate because the gate is open,” Daltry said. “There are plenty of days when no water is going back and forth when they keep the gate shut.”