The beach at Lake Hiawatha and Lake Harriet's Southeast Beach have been closed due to excessive E. coli readings, the Minneapolis Park and Recreation Board announced Tuesday.
The board's regular sampling found that the levels exceeded state guidelines.
No one has become ill, and the beaches will reopen when the bacteria levels are within state guidelines. The water will be tested again on Monday.
It's not uncommon for Minnesota beaches to be closed due to E. coli contamination in the summer, since it can be produced by waste from geese, ducks and other wild animals as well as boaters dumping waste overboard.
The bacteria can sicken swimmers, causing diarrhea, abdominal cramps and more serious problems.