A Denton sewer line break earlier this week triggered a spill of more than 2.6 million gallons of raw sewage into Pecan Creek, which empties into Lewisville Lake.
According to a city news release, the spill occurred in a remote area far from water supply intakes and was not expected to affect local drinking water supplies.
However, the spill was large enough that officials are urging the public to avoid the creek as well as the channel downstream from the Pecan Creek Water Reclamation Plant until cleanup work is finished.
A fisherman called the Texas Commission on Environmental Quality on Sunday to report dead fish and a sewage smell near where Pecan Creek enters Lake Lewisville.
City crews first checked systems that were working properly at the reclamation plant and then began monitoring water quality in Pecan Creek by boat, starting at the lake and moving upstream.
They found the problem south of the reclamation plant: A break in a large sewer line led to the overflow.
According to the news release, recent rains triggered a slide near a bend in the creek, putting pressure on the line and causing the break. Crews worked around the clock from Monday afternoon until Tuesday morning to remove and stabilize the soil, plug the broken sewer line and reroute sewage to the plant.
The overflow itself was stopped Monday evening. State inspectors visited Tuesday, officials said, as city crews continue to stabilize the failed slope and repair the line. City staff also placed aeration devices in the creek to help raise oxygen levels in the water, and is continuing to monitor water quality.
City officials say they believe the release began about 3 p.m. Saturday and continued until 11:30 p.m. Monday. They estimated the spill volume was 2,601,825 gallons of domestic sewage.
The impact of the spill dissipated rapidly once the water flowed out of Pecan Creek and into the lake, according to lake monitoring data.
City officials urge anyone who comes into contact with water or soil potentially affected by the spill to bathe and wash clothes thoroughly as soon as possible.