NEWBURY, N.H. — In response to public outcry, the state is stepping in to help make improvements to the wastewater treatment system at Mount Sunapee Resort, despite maintaining that it does not violate state environmental standards.

The Department of Natural and Cultural Resources, which oversees Mount Sunapee State Park, has applied for grant funding through the state’s clean water revolving fund that it will use to conduct a study of the resort’s wastewater treatment system and to “help pay” a contractor to make improvements.

“With the privilege of operating on public land comes the responsibility to invest in long-term stewardship,” Natural and Cultural Resources Commissioner Sarah Stewart wrote in a letter this week to resort manager Susan Donnelly. “Modernizing the wastewater system is not simply a regulatory obligation — it is a moral one.”

Stewart is responsible for approving the resort’s annual operating plan per a lease agreement between parent company Vail Resorts and the state of New Hampshire. The plan dictates when the resort can be open, what activities it can offer, and infrastructure and logistical matters such as parking, stormwater management, snowmaking and wastewater management.

On Monday, Stewart approved the plan that governs mountain operations through next winter with some conditions. The wastewater system improvements are meant to address consistent concerns from environmental groups about the condition of the current lagoon system.

In her approval, Stewart also mandated that Mount Sunapee leadership share their improvement plans and environmental assessments of the septic system with her department.

These documents are already required by the state’s Department of Environmental Services and the DNCR plans to “facilitate” sharing the information.

DES publishes communications, plans and assessments for projects online, but at a June 3 meeting of the Mount Sunapee Advisory Council, members of the Newbury Conservation Commission said required reports and updates for the resort were not available.

“Public trust in the system is weakening not because of a specific violation, but because the infrastructure itself is from a different era,” Stewart wrote.

Constructed in 1970, the current wastewater system at Mount Sunapee relies on evaporation from three unlined sewage “lagoons.” Adjacent fields are treated with liquefied waste during non-winter months. Environmental groups have been raising the alarm about the system for more than a year, arguing it contaminates groundwater near Lake Sunapee and adjacent wetlands and streams.

DES representatives have denied these claims and maintain that the system does not violate any permits or state regulations and is functioning properly, which constrained what Stewart could ask of the resort.

“Under current law and regulation, DES cannot mandate the replacement of a system that is functioning as permitted,” Stewart wrote as an introduction to her work-around.

The June 3 meeting of the Mount Sunapee Advisory Committee, a group of stakeholders who advise Stewart on mountain operations, drew a vocal crowd concerned about the septic system and gave environmental groups and DES regulators the chance to lay out their cases.

At that meeting, the Lake Sunapee Protective Association and other environmental groups requested that the resort get to work to replace the 55-year-old septic system by the end of 2026 and requested more transparency and community involvement in the process.

For its part, the Lake Sunapee Protective Association, which also holds a seat on the advisory council, is lauding Stewart’s decision as a “win not only for the environment but also for our local economy and quality of life,” Executive Director Elizabeth Harper wrote in a news release.

Going forward, Stewart wrote that DNCR is drafting a request for proposals for the treatment system study and plans to reconvene the advisory council to review the proposal. She did not include a timeline for the study or improvement work.

As for the resort, they are in “close communication” with DES and DNCR about the “state-permitted and functional” system and “will continue to work in partnership with DES and DNCR moving forward on a feasibility evaluation of the wastewater system,” Courtney DiFiore, senior communications manager for Mount Sunapee, said via email Monday.

Clare Shanahan can be reached at cshanahan@vnews.com or 603-727-3216.