Suffolk officials say the design phase of a sewage expansion project in downtown Oakdale and Sayville will begin this year in an effort to mitigate pollution in the Great South Bay.

Environmentalists say updated sewage systems in those communities is crucial to keeping Long Island's waterways clean.

Officials say Suffolk is not like other municipalities in the tri-state area. The majority of its wastewater treatment relies on individual cesspools and septic systems. More than 360,000 homes are in need of an individual system.

Nitrogen leeching from current sewage systems has caused polluted waterways and brown tide, environmentalists say.

The design phase of the project will cost about $5.5 million. It will also include sewage expansion in the area around MacArthur Airport in the Town of Islip.

County Executive Steve Bellone says they reallocated funds to pay for the design phase of the project. He says officials are trying to find a way to pay for the building of the project amid an estimated $180 million budget deficit in Suffolk.

Officials hope to start the project in 2018. It is expected to cost $35 million.