Updated: This story has been updated. The form of bacteria in Sugarloaf lake was misstated in an earlier version.

People making plans to go out and enjoy one of the five public beaches in Washtenaw County this weekend should steer clear of Sugarloaf Lake in the Waterloo Recreation area.

The Washtenaw County Environmental Health Department had to close the Lyndon Township beach, as well as Bruin Lake, earlier this week due to high coliform bacteria levels in the lake, said Kristen Schwegighoefer from the environmental health department.

The bacteria levels in Bruin Lake have since returned to acceptable levels as set by the Department of Natural Resources and the Environment, she said.

• Check out other beaches closed throughout the state.

During the swimming season - which lasts from Memorial Day to Labor Day each year - the county takes five samples a month at each beach. It collected samples with high levels of bacteria on July 9 and closed both beaches the following Monday when results came back.

Coliform bacteria levels can rise in lakes for a variety of reasons, including a large number of swimmers, high water temperatures and the presence of geese and other critters, she said. Large rain storms can also cause runoff to pour into a lake, increasing the amount of bacteria in it.

The water at Sugarloaf Lake is being tested again, and the lake could reopen as early as next week, depending on the results of the tests, officials said.

Tina Reed is a reporter for AnnArbor.com. She can be reached at tinareed@annarbor.com or at 734-623-2535.