Mobile Area Water and Sewer Service, the utility providing drinking water for most Mobile County residents, is closing Big Creek Lake to recreational boating and fishing, effective immediately.

“Protecting our drinking water supply is our top priority,” Bud McCrory, director of MAWSS, said in a news release. “While we recognize the impact this may have on recreational users, the closure is necessary to mitigate risks posed by invasive species and to ensure that Big Creek Lake remains a safe and reliable source of drinking water for generations to come.”

Big Creek Lake is the source of drinking water for MAWSS customers. The utility has struggled to protect the lake from invasive species in the past, primarily Giant Salvinia, a floating fern that creates mats on the surface of the water, blocking sunlight for other aquatic plants and disrupting the water quality.

For nearly a year from 2021 to 2022, MAWSS closed Big Creek Lake to recreational use while the utility tried to combat Giant Salvinia in the lake.

When the lake re-opened to recreation, MAWSS took steps to prevent another salvinia outbreak, including requiring users to wash their boats before entering the lake and limiting the hours the lake was open.

“Despite these efforts, the closure is now viewed as the most effective and sustainable solution to protect the lake and the drinking water supply,” the news release said.

Big Creek Lake provides around 41 million gallons of drinking water per day. Around 70% of Mobile County residents are served by the lake.

There are other threats to Big Creek Lake as well. Last year, the MAWSS board of directors passed a resolution allowing the city of Mobile to annex the lake and “the area surrounding Big Creek Lake.” Candace Cooksey, a spokesperson for Mobile Mayor Sandy Stimpson, said at the time annexing the lake and surrounding watershed would be to bring it under the city’s zoning regulations to protect from any future industrial development.

But those efforts stalled following pushback from nearby residents, who were afraid any annexation would lead to their property being annexed as well. And Cooksey said the city did not have a pathway to annex the lake yet.