State environmental officials yesterday awarded the city of Glen Cove and the towns of Huntington and Oyster Bay a $6.8-million slice of the state's $1.75-billion Clean Air Clean Water Bond Act.

Huntington's sewer district will receive $3.2 million to construct a treatment system designed to glean nitrogen from 2.5 million gallons of wastewater a day.

Oyster Bay will get $207,760 for a project to treat stormwater runoff into the Long Island Sound and install a filtration system for water entering the Sound in the Turtle Cove area.

And after receiving a $1.4-million federal environmental grant Tuesday, Glen Cove will get another $3.4 million in state money to rebuild bulkheads along Glen Cove Creek and reduce its nitrogen levels. Mayor Thomas Suozzi will use the grants to spearhead a $280 plan aimed at transforming the city's blighted waterfront into a boater and tourist attraction. He said the cleanups will have a trickle-down effect.

"Nitrogen has no respect for boundaries," he said yesterday at a city hall news conference. "It's important for us to remember that this will help the entire Long Island Sound."

Environmentalists have identified nitrogen as a key problem for the Sound because it's a nutrient for summer algae growth. When algae die, they soak up the dissolved oxygen needed by marine animals.

The projects, among 18 statewide, are to help meet a 15-year goal to decrease by 58.5 percent the nitrogen discharged into the Sound. It was set in February by the state's Long Island Sound Study Policy Committee. Much of the money is from the clean air and water bond act, approved by voters in 1996.