MATTOON, Ill. (WCIA) — Just days after being reopened, Lake Mattoon is closed to swimming after city officials said there are still signs of a harmful algal bloom in the water.
The beach was closed for three weeks after that bloom wreaked havoc on the city’s water supply, resulting in a do not drink order. Even after the order was lifted on July 18, the lake remained closed pending treatment of the water, which was delayed by low levels of oxygen in the water.
Finally, on July 29, Lake Mattoon was reopened to swimming and boating.
But it didn’t last. On Thursday, the city announced it was closing the beach at Lake Mattoon because the algal bloom is still indicating a presence in the water.
Out of an abundance of caution, the beach is closed until further notice, pending additional test results from samples being collected on Friday. People are advised to avoid contact with the water.
The city has contracted an outside organization to treat the water, officials said, but oxygen in the water is still low. Treatment has been postponed and won’t happen until conditions are favorable to do so.
Officials did not say there are issues with the city’s drinking water. The most recent test a week ago indicated a toxin level of 0.000 parts per billion.

