Suffolk County is working with New York Sea Grant to analyze ways to reduce warm weather algae blooms, which can sicken people and kill marine life, officials and scientists said at a conference.

With harmful algae blooms likely to again mar swimming and fishing this summer, Suffolk officials and scientists from several states discussed causes, pitfalls and some solutions at the conference this month in Great River.

“We don’t have a blueprint for what’s causing these harmful algae blooms and what to do about it,” Walter Dawydiak, director of the county health department’s Division of Environmental Quality, told Newsday after addressing the conference.

Dawydiak said the analysis is the first time in 15 years the county has worked with Sea Grant on such an analysis. New York Sea Grant is a cooperative program of SUNY and Cornell University.

Long Island’s five types of algae blooms — blue-green, brown, rust and two types of red — are a bit unusual for such a relatively small area, said Christopher Gobler, a Stony Brook University professor.

Gobler invited experts from Maryland, California and the National Oceanic and Atmospheric Administration to speak about harmful blooms in the Great Lakes and the San Francisco and Chesapeake bays.

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Though Lake Erie was cleaned up four decades ago, phosphorus pollution from agricultural runoff has returned because all of the sources were not dealt with, experts said.

William Wise, New York Sea Grant director, said by the summer the public should see a preliminary draft outlining “what Suffolk can do, steps it can take, to limit the frequency and occurrence of algae blooms over the next several decades.”

The final plan should be finished by year-end, he said.

County Executive Steve Bellone, who called nitrogen “public water enemy No. 1,” proposed a $1 per 1,000 gallon surcharge on water to fight the pollutant, the main cause of harmful algae blooms, by upgrading cesspools, connecting homes to sewers and assisting municipalities with wastewater needs.

Dawydiak noted 360,000 of Suffolk’s homes rely on septic systems and cesspools, generating about 70 percent of the nitrogen pollution in the area’s surface water.

Modernizing 60,000 of those systems could cost $1 billion to $2 billion, he said, so Suffolk wants to target improvements where they do the most good, perhaps by focusing on systems located in the most vulnerable subwatersheds.

“We want to make sure we have the best information,” said Dawydiak, explaining the Sea Grant-Suffolk endeavor emphasizes monitoring, management and research.

Gobler said, for example, more frequent monitoring might prove valuable, as weekly assessments of water quality can miss important fluctuations.