The Sacramento Municipal Utility District has advised against swimming in the Rancho Seco Recreational Area lake through the Labor Day holiday.
SMUD, which tests the lake water regularly, found elevated levels of bacteria disseminated by lake waterfowl.
The no-swimming advisory, the first of its kind issued by SMUD regarding the lake, is scheduled to end Tuesday.
The advisory does not effect boating or fishing on the lake. The park's drinking water, which does not come from the lake, is safe, according to SMUD.
The Rancho Seco Recreational Area, owned and operated by SMUD, is 25 miles south of Sacramento and about 15 minutes east of Highway 99 on Twin Cities Road.
