EASTHAM — Last month’s news that the town had qualified for a renewable $50-million low-interest loan from the state Dept. of Environmental Protection for a sewer system to protect the Salt Pond and other estuaries from nitrogen has brought more than a decade of planning abruptly into the present.

The requirement that Eastham address excess nitrogen is rooted in the 1972 Clean Water Act. More than 40 years later, the settlement of a lawsuit against the EPA for failure to follow its own rules put pressure on Cape Cod towns, including Eastham, to clean up their watersheds. Another decade passed before a vote to build a sewer system here took place at the 2023 town meeting. Last year, Mass. DEP approved the town’s Targeted Watershed Management Plan, which identified the DPW site as the best location for a treatment plant.

The need to respond quickly to the state’s loan offer led Town Manager Jacqui Beebe to acknowledge that “this is going to be a very hard sell for the community.” She organized a May 7 session at the Eastham Public Library “to make sure people begin to understand what this is and what this isn’t.”

Beebe, joined by Health Director Hillary Greenberg-Lemos and two members of Abington-based subcontractors Apex Corp., presented a preliminary design blueprint for the wastewater treatment facility.

In the blueprint, the processing plant is at the back of the town’s 19-acre DPW site, close to the metal pile at the Eastham Transfer Station. Six sand filtration beds will be located between the facility and Old Orchard Road but will not be visible from the street, thanks to buffer plantings. The distance from the road to the processing building is 500 feet.

But the 20 or so townspeople at the session were worried about smells coming from the treatment facility, noises from trucks, and the traffic disruptions associated with construction, which, if the project is approved at a special town meeting on June 23, would start in 2026.

“We want to do everything possible to reduce the impacts to the neighborhood,” Beebe said.

Unlike in Orleans and Yarmouth, she said, there would be no trucks unloading septage into the plant. Everything the plant treats would come through underground pipes connected to the 786 parcels located around Salt Pond’s watershed, which is a focus of the cleanup.

The treatment building, Beebe said, would have a footprint of about 80 by 150 feet. Sludge and grit would be removed inside the building and transported off-Cape. Treated effluent would then be poured into sand filtration beds on the DPW parcel.

Beebe said the town would seek to reconstruct the natural buffer between the DPW and Old Orchard Road — which she noted had become unattractive in recent years — with new fencing, trees, and other plantings.

Edward Callahan, who lives on Kettle Hole Road, criticized the DPW site’s proximity to a residential area, pointing out that houses were visible on an aerial map of the proposed facility. Beebe responded that the town had considered building the treatment plant at T-Time and the North Eastham sand pit, but that those sites ran a higher risk of contaminating drinking water, according to a 2022 study by the engineering firm GHD.

Some audience members questioned the need for a treatment plant at all. Beebe offered a two-part answer.

First, she said, voters do have a choice to make at the special town meeting. If they accept the loan from the state, it will renew each year until the $170-million project is complete — a provision that Assistant Town Manager Rich Bienvenue said won’t be guaranteed if the town applies for the same loan next year.

If the town chooses not to accept the loan, most Eastham parcels, including ones not located near the proposed sewer system, would be required to install an innovative/alternative (I/A) septic system within the next five years to comply with current DEP regulations as outlined in the Cape Cod Commission’s “208 plan.”

Properties that fail to install an I/A system likely wouldn’t pass a mandatory inspection, and owners could be at risk of legal action by the DEP or EPA.

Bienvenue said the I/A route would be expensive for homeowners. He put his “conservative” cost estimate at $50,000 per property and the yearly cost of maintenance at $4,000.

The Salt Pond is only one of four Eastham waterways the EPA identified as threatened. Nauset Marsh, Rock Harbor, and Boat Meadow were the others, Beebe said.

Beebe said that the town chose to focus on Salt Pond for a practical reason: the other estuaries are shared with neighboring towns. To clean those up, there’s a chance a collaboration with Wellfleet or Orleans could be worked out. For Salt Pond, though, it was clear that the town would need to go it alone.

The reduction of nitrogen in Salt Pond, Beebe said, represents the first half of the town’s proposed sewer project. The second half likely wouldn’t begin for at least a decade.

“We don’t know how long it’s going to take us to get to phase two,” she said. “It really depends on what happens with phase one.”