Brevard County health officials are warning residents about a potential toxic, blue-green algae bloom in Lake Washington after the Florida Department of Health found the type of bacteria in a water sample.

This is the second alert this year for Lake Washington, which is where two-thirds of Melbourne's water comes from.

Blooms occur when algae grow rapidly and produce floating mats and a bad smell.

A nonprofit group that monitors the 310-mile-long St. John's River said it's concerning for this type of bloom to happen so early in the year.

"We are very concerned we are going to see an increased outbreak of this toxic, green slime," Lisa Rinaman said. "Because we are seeing an increase in nutrient pollution throughout the St. John's River, especially in the headwaters area in Brevard County, there's not a plan from state agencies to reduce these pollution threats." 

Rinaman added that experts are concerned more blooms could form as the hot summer months approach.

While the Florida Department of Environmental Protection responded to a request for comment, the department has not yet sent a statement.

Officials with the city of Melbourne said public works tests and monitors both the raw and unfinished water for algae toxins and can adjust operations so that nothing gets from the raw to the treated water.