TOLEDO, Ohio (AP) — Environmental groups are suing the U.S. Environmental Protection Agency over its decision not to declare Ohio's western end of Lake Erie impaired by toxic algae.

The lawsuit filed in Toledo on Tuesday says the lake should be designated as an impaired watershed because the algae blooms are preventing the lake's waters from meeting basic quality standards.

The algae blooms in the shallowest of the Great Lakes have fouled drinking water in recent years and are a threat to fish and wildlife.

Ohio regulators have resisted calls to designate its portion of the lake an impaired watershed.

Environmental groups were upset after the EPA announced in May that it wouldn't make the designation and pave the way for increased pollution regulations.

An EPA spokeswoman declined to comment on the lawsuit.