State and Suffolk County officials are preparing to take the next steps in a plan to build a multimillion-dollar sewage treatment system designed to clean up the polluted Forge River and protect homes and businesses in Mastic from flooding.

Environmental advocates and some residents have for years said a modern sewer system is needed to replace cesspools that leak harmful nitrates into the groundwater, creating algae blooms that starve fish of oxygen.

Help finally arrived after superstorm Sandy flooded the Mastic area. The 2012 storm persuaded federal and state authorities to provide funding for five projects — including the Forge River plan — to harden Long Island shorelines against future storms.

Construction of the Forge River project is expected to cost about $168 million, Suffolk Public Works Commissioner Gil Anderson said. Officials hope federal and state funds will pay the entire cost, said Legis. Kate Browning (WF-Shirley).

The Forge is Suffolk’s most algae-infested river, according to a report by the Governor’s Office of Storm Recovery.

The Forge River is seen from Riviera Drive in Mastic on Monday, Jan. 11, 2016. Suffolk County and state officials are planning to build a multi-million-dollar sewage treatment plant in Mastic to protect the area from flooding and save the Forge River from pollution. The river is choked with algae caused by nitrates that seep from cesspools. Photo Credit: Newsday / John Paraskevas

“Nitrogen levels to the Forge River will be dramatically reduced once we have sewers,” Browning said in an interview, recalling fish die-offs in the river caused by excessive nitrates. “You actually could see the fish jumping up out of the water to try to get oxygen.”

advertisement | advertise on newsday

The county plans to create a sewer district on the west side of the river, south of Sunrise Highway and east of William Floyd Parkway. The sewage treatment plant would be built on Brookhaven Town-owned land at Calabro Airport in Shirley. Browning said the district would serve up to 79 businesses and more than 2,000 homes.

The county plans to hold a referendum later this year or next year asking residents to approve the plan, Anderson said. Construction is expected to start in 2018 and should be completed in two to three years, he said.

A public meeting, part of the state environmental review process, is scheduled for 6 p.m. on Jan. 26 at William Paca Middle School in Mastic Beach.

Superstorm Sandy in 2012 opened a breach on Fire Island that has helped to flush the river, improving conditions somewhat. The storm also flooded riverbanks, heightening concerns that antiquated cesspools could be destroyed by more flooding.

The Forge River is seen from Montauk Highway in Mastic on Monday, Jan. 11, 2016. Suffolk County and state officials are planning to build a multi-million-dollar sewage treatment plant in Mastic to protect the area from flooding and save the Forge River from pollution. The river is choked with algae caused by nitrates that seep from cesspools. Photo Credit: Newsday / John Paraskevas

Local residents’ views of the sewer plan are mixed.

Mastic resident Ron Lupski, president of Save the Forge River, said he welcomes the plan, although he acknowledges some residents of his working-class neighborhood do not.

“I would pay [for] it through my taxes,” said Lupski, a union carpenter. “It’s a poorer community, so some people might not be able to afford it.”

Brookhaven Town officials have said they support the project. County and town officials are discussing details of where the plant would be located at the airport, Supervisor Edward P. Romaine said.

“It would be a shame if this project wasn’t completed,” he said. “This is a project that is of great import for cleaning up the Forge River and providing effective sanitary waste disposal, which is critical to the area.”

The Forge River is seen from Riviera Drive in Mastic on Monday, Jan. 11, 2016. Suffolk County and state officials are planning to build a multi-million-dollar sewage treatment plant in Mastic to protect the area from flooding and save the Forge River from pollution. The river is choked with algae caused by nitrates that seep from cesspools. Photo Credit: Newsday / John Paraskevas