Cutting nitrogen pollution in Suffolk’s eastern South Shore Estuary Reserve will require a mix of solutions as the source of the contamination varies among the watersheds, according to a new report.
Wastewater has long been pegged as the prime culprit in curbing nitrogen pollution, which since 1985 has spawned algae blooms and killed fish and shellfish in Long Island waters.
Released Tuesday, the new study for the first time quantified how much nitrogen wastewater contributes — 65 percent of the total — followed by fertilizer at 20 percent and air pollution that mixes with water particles at 15 percent.
The analysis by the Stony Brook University School of Marine and Atmospheric Sciences offers policymakers a blueprint for seven watersheds from the Moriches to Shinnecock inlets. The study ranked the seven by priority: Moriches West, Quantuck Bay near Westhampton, Shinnecock Bay West, the Heady and Taylor creeks by Southampton, Moriches East, Moriches Middle and Shinnecock Bay East.
The costliest approach, building new sewers, was recommended as the top strategy for only two areas — Moriches West and Shinnecock Bay West.
Upgraded cesspools and septic tanks, recommended for all areas, were the first priority in Quantuck Bay, Moriches Middle and Shinnecock Bay East.
Controlling development was recommended as a second priority for Shinnecock Bay West and Quantuck Bay.
Only in two areas — Heady and Taylor creeks and Moriches East — was “controlling buildout” the top recommendation, according to the study, undertaken for the New York State Department of State, which plays a role in regulating the coast.
However, some environmentalists say tighter building limits are needed.
Much of Suffolk’s water pollution resulted from antiquated rules that allowed too many residences and commercial buildings to go up without sufficient wastewater treatment.
While 1.5 million people live in Suffolk, around 70 percent of homes lack sewers.
“We’re not going to build our way out of a water crisis, we built our way into a water crisis,” said Adrienne Esposito, executive director of Citizens Campaign for the Environment, an advocacy group based in Farmingdale.
The quickest and least expensive solution cited by other environmentalists — using less fertilizer — was recommended for only two areas: Heady and Taylor creeks and Moriches Middle.
County Executive Steve Bellone views cleansing Suffolk’s waters as a signature issue and his spokeswoman says the new report confirms his policy.
“It is yet another science-based study that finds the largest single threat to water quality are cesspools and septic systems,” she said by email.
“The study underscores the importance and urgency of the County’s efforts to set the stage for a well-planned evolution away from the use of nonperforming cesspools and septics to active treatment,” she added.
At stake is Suffolk’s quality of life as well as the multibillion industries of tourism, recreational boating and fishing, officials said.
“The health of the water of the South Shore Estuary is the cornerstone of the region’s economy,” New York Secretary of State Rossana Rosado said in a statement.
One aspect of Suffolk’s strategy, urging homeowners to install pollution-cutting wastewater systems, is working in its favor as the price is falling.
In the last year, the cost of such systems has dropped to about $10,000 to $15,000 from $20,000, Esposito said.
The report also examined how long nitrogen lingers by examining “residence time,” the amount of water in a body of water divided by the rate new water is added or lost.
Perhaps not surprisingly, areas near ocean inlets had the quickest turnover: 9 days for Moriches Middle and Shinnecock Bay East.
At 26 days, the worst performer was Quantuck Bay; it also had the worst water quality.