Minneapolis parks officials have temporarily closed the 32nd Street beach on Lake Calhoun and the Lake Hiawatha beach because of elevated levels of E. coli bacteria.
The popular beaches will be retested and will reopen as soon as possible, the parks department said.
Contamination typically comes from waterfowl or storm water that washes into the lakes after rain. Minnehaha Creek also flows through Lake Hiawatha, after starting in Lake Minnetonka.
Excelsior beach on Lake Minnetonka is also closed. State health officials reported three cases of E-coli infection among people who swam near the Big Island in that lake, a popular gathering place for boaters. Hennepin County has also closed the Snelling Lake beach at the Fort Snelling State Park.