Published: Aug 14, 2013 6:38 PM EDT

FORT MYERS BEACH, Fl. - Brown water and now grayish sludge is causing concerns about a canal in a Fort Myers Beach neighborhood. Experts say the fresh water run-off from Lake Okeechobee is affecting waterways throughout Southwest Florida.

"They just put their boat in the water and they came back and their slip was covered in that stuff," said resident Ted Homer.

Homeowners who back up to this Fort Myers Beach canal say the color went from blue to brown.

"One day the water was beautiful and the next it looks like mud. It looks like sewer and they'll be stuff floating around on the tops some mornings, days it's gross," said neighbor Corey Putman.

Eric Milbrant, PhD with the Sanibel-Captiva Conservation Foundation says the slime is actually microscopic blue-green algae that grows on the bottom of canals and forms these large floating mats.

"During the day they produce Oxygen and bubbles and the mats will break apart and float during the middle part if the day and then at night they'll use that oxygen and the bubbles and it'll sink down to the bottom," Milbrant said.

The doctor says he hasn't seen an example like this in awhile and says it's another symptom of too many nutrients caused by heavy rains, hot weather and fresh water releases from Lake Okeechobee.

"The canals are a perfect place for this particular algae to grow because it can grow attached to sea walls, docks and other structures," he said.

"It's getting worse, the sludge part of it. At first there wasn't the sludge and now it's getting really bad," said resident Tim Putman.

Experts say it's hard to know how long these conditions will last but say if there is enough fresh water and enough rain to continue fueling these blooms, we could see this type of algae well into the Fall.