OKLAHOMA CITY (AP) - Oklahoma City officials say blue green algae has been found at two of its lakes.

Officials said Friday that the city's Water Quality department has treated Lake Hefner and Lake Overholser and will continue to monitor the algae levels daily.

Officials say swimming isn't allowed on Oklahoma City lakes, but they want visitors to avoid areas with visible algae accumulation.

Blue green algae are microscopic organisms that are naturally present in lakes and streams. Most blue green algae aren't toxic, but toxins harmful to humans and animals can be produced in some algae blooms.

The Grand River Dam Authority discouraged people from swimming in Grand Lake.