SOUTHAMPTON - Suffolk County residents are being warned to stay out of the water at a few popular spots because of a dangerous, toxic algae bloom.

High levels of toxic blue-green algae have been found in Lake Ronkonkoma. Algae blooms have also been discovered in Mill Pond in Water Mill and Lake Agawam in Southampton Village.

Officials and environmentalists say exposure to high levels of blue-green algae can cause serious health problems.

It's believed that the algae blooms are being fueled by warmer water temperatures and elevated levels of nitrogen and phosphorus in the water.

The state DEC recommends not swimming or letting pets in the water for now. Some experts say that the blooms may be here for a while.

"Typically, these events can go on all the way into the fall," says Christopher Gobler, of Stony Brook University. "We've had some events going all the way into November."

Environmentalists say the algae blooms mean that Long Island needs to replace its aging septic and sewage systems to reduce nitrogen levels in the waters.