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City of Tyler: low lake level 'not result of anything going on at the dam'


The city of Tyler is moving forward with plans to repair the Lake Tyler dam, after discovering seepage back in 2010.

Some residents said they believe a leak in the dam is to blame for low water levels in the past couple of years, but city officials say that the dam, built in the late 1940s, has always had a seepage problem.

"It was designed to the best engineering practices at that time," said Tyler Utilities and Public Works Managing Director Greg Morgan. "However it was constructed on a sand foundation and as a result of that, the dam has probably seeped since the beginning."

The city said documentation about the leak dates back to 1978, but during an inspection in 2010, they observed boils, a mixture of soil and water seeping under the dam.

Tyler and the Texas Commission on Environmental Quality have measured a flow of about 30 minutes per minute leaking under the Lake Tyler dam, but they say that compared to the size of the lake, it isn't enough water to make a dent in the lake levels. In fact, they say it would take 91 years for that amount of flow to lower the lake by one foot.

But the city did find the problem worthy of spending $4.5 million to build a deep soil mixing cutoff wall, which will extend 60 feet into the ground just downstream of the dam and stop any further seepage.

"It will seal off the boils and the seepage along the face of the dam and protect the structural integrity," said Morgan.

But could the seepage be the reason Lake Tyler is so low? Not according to city officials.

"The changes of the lake elevation is pretty indicative of the average evaporation that we see at this time of year," Morgan said. "That is coupled with a small drainage basin and a lack of rainfall."

In fact, water data shows that six months ago, the lake was even lower at nearly four and a half feet below normal. Looking even further back, the city said the lake went as low as eight feet below normal in 2007, a figure they believe to be the record low. But today, the lake elevation is hovering just around four feet below normal.

There also has not been the rain to fill the lake back up. The area has seen nine inches less than normal since January 2013 and only two-tenths of an inch so far in July. That rain is key to re-filling the lake.

"The answer is it's not the result of anything that's going on at the dam," Morgan said. "It's 100 percent the result of small drainage basin, lack of rainfall and evaporation."

The Texas Commission on Environmental Quality, who regulates dams in the state, also agree with the city that the dam is not the cause of low lake levels. They said the lake is behaving normally given recent drought conditions.

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