University professor researches water quality of University Lake

For hydrology professor Jun Xu of Louisiana State University, the issues plaguing University Lake — like shallow depth, pollutant accumulation and excess sediment and nutrients — could be water under the gate.

Xu and his graduate students study the quality of several major Louisiana bodies of water, including University Lake, the largest of the Baton Rouge lakes. Xu said a sluice gate, a gate that controls the flow of water, could serve as an alternative to the Baton Rouge Area Foundation’s proposal to dredge University Lake as parts of its master plan.

“People want to dredge, which would be certainly helpful, but it is not a long-term solution, and that is because after they dredge, the material will accumulate again,” Xu said. “The lakes were dredged many times before in the past 70 to 80 years.”

The lake is a man-made and artificially maintained ecosystem, Xu said. Despite the dredging, which took place in the early ’80s, garbage, pollutants, sediments and excess nutrients continue to collect in University Lake.

“My graduate students go there frequently, and we have found everything possible,” Xu said. “We even found a refrigerator, a couch, a sofa. People throw everything in, even big pieces of plastic.”

Xu proposes replacing the existing gate between University Lake and the Corporate Canal with a sluice gate. He said the current gate has a damming effect, causing pollutants, sediment and garbage to build up over time, as if the lake is a sink or a bowl.

“If we lifted this gate today, this whole lake would disappear because the water here is artificially maintained at this level,” Xu said. “If you go there, you will see the lake’s water is about 10 feet higher than the canal.”

If the existing gate were removed, the water would flow into Corporate Canal because of the height difference between the two bodies of water.

Instead of leaving the space between the two bodies of water open to permanently separate the two, Xu said the opening could be replaced with a sluice gate, which can be raised and lowered based upon the calculated amount of time it takes to flush the desired amount of the lake’s contents. After the lake is flushed and the gate lowers, fresh rainwater would replenish the lake.

Xu and his graduate students began studying the water quality of University Lake in 2008. In addition to the lake gate, they identified three other issues: stormwater runoff, algal bloom and sediment resuspension.

Storm drains line the streets surrounding University Lake, funneling excess stormwater into the lake. Xu said the waters flowing through the storm drainage system could be filled with pollutants, like pesticides and fertilizers used on nearby lawns.

Xu said the contaminated stormwater draining into University Lake stimulates algae growth and causes algal bloom, a rapid increase in algae population that often causes water discoloration. As the algae die off, they sink to the bottom of the lake and decay, consuming dissolved oxygen in the water. Xu said the lake’s dissolved oxygen level dropped so low that fish began to die in large numbers because of extreme oxygen deprivation.

When wind blows over University Lake, the turbulence causes the water to stir, which suspends the sediment resting at the bottom of the lake, clouding the water and reducing visibility.

Xu said University Lake’s average depth is around 2 to 3 feet. When he and his students lowered a device into the water to test visibility, the object became indiscernible after being lowered just 6 inches into the lake.

“In the lake at the bottom, you have all kinds of material — like dirt, like organic debris, like tree branches, grasses, all kinds of stuff,” Xu said. “This material will be flushed out when you open the gate, so that is basically like a dredge, but you’re using a gate to dredge the lake.”

 

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