Reopened: How a Closed Beach Gets the All-Clear

When a Minneapolis lake beach closes for elevated E. coli, the Minneapolis Park and Recreation Board does not set a fixed shutdown period. Staff sample bacteria levels weekly between Memorial Day and Labor Day, post a closure at the beach and on the agency's Lake Water Quality Map, and reopen only after routine sampling shows levels back within state guidelines.

Rain is the usual cause. "It's just that we and geese like a lot of the same things," Rachael Crabb, the Park Board's water resources supervisor, told the University of Minnesota Water Resources Center, describing how storms wash waterfowl droppings off the land and into the lake. Once the rain passes, counts often drop quickly, which is why many bacteria-related closures last only a day or two.

Some beaches stay down far longer. Lake Hiawatha, which has a large stormwater outfall, was closed 388 days over the past 11 years and spent six straight weeks shut last summer, the Water Resources Center reported. The 2024 season produced 15 closures citywide, the most in 11 years, after the wettest summer in that span.

The system errs toward caution. Because the Park Board waits for a confirming sample rather than guessing at a safe reopening date, a beach may occasionally stay posted a little longer than the water strictly requires. The Lake Water Quality Map, updated after each round of testing, lets swimmers see where a given beach stands rather than driving to the shore to find out. The sign stays up until a real test says otherwise, and comes down when one does.