NEWBURY, N.H. — Conservation groups are raising concerns about a plan to expand parking at the Mt. Sunapee Ski Resort, the mountain’s aging wastewater system and the potential contamination of Lake Sunapee.

Vail Resorts, which leases the ski area from the state, has moved forward with plans to build an additional parking lot on the Mt. Sunapee Access Road and increase the size of an existing lot.

The problem, for the Newbury Conservation Commission, is that the new lot would sit directly downhill from the resort’s wastewater system, which includes three sewage lagoons and three spray fields that distribute treated waste over a grassy area using sprinklers.

The NCC contends that the construction of a parking lot would cause polluted runoff to enter nearby Beck Brook, and Lake Sunapee, into which Beck Brook flows, about a mile away.

On Wednesday, the Newbury Conservation Commission submitted a statement to New Hampshire Department of Natural & Cultural Resources Commissioner Sarah Stewart requesting that the project — which would add about 275 parking spaces — be put on hold pending the creation of a park-wide stormwater management plan and an end-of-life plan for the wastewater facility, which is more than 50 years old.

“The NCC feels there will be groundwater flow, with a significant black water component, from the spray fields toward the parking lot. Since the new parking lot will be in the flow path, the contaminated groundwater will likely emerge as surface water and then flow into Beck Brook, a feeder brook for Lake Sunapee,” the NCC said in its statement.

The water quality in the lake is important because of the lake’s role in the region’s recreational economy and in providing drinking water to the town of Sunapee.

The new parking lot project was approved by the Department of Natural and Cultural Resources as part of the resort’s 2022-23 operating plan, according to Stewart, the DNCR commissioner. The project has received permits from the Department of Environmental Services for groundwater discharge and wetlands dredging but is still awaiting an alteration of terrain permit.

Stewart declined to comment further on the project, saying that “all public feedback is welcomed and valued, and helps ensure transparency and the proper stewardship of our natural resources.”

Peter Disch, Mt. Sunapee Resort’s general manager, could not be reached for comment by deadline and Vail’s spokesperson was not able to address questions about the project’s timeline.

In its statement, the NCC also noted concerns that the dam containing the lagoon appears to show seepage in three different points.

“There’s concern about a catastrophic failure of the dam system, which would release tons of contaminants into the lake and potentially cyanobacteria,” Friends of Mt. Sunapee President Steve Russell said Friday.

But the larger problem seems to be the wastewater system itself. After conducting site visits, members of the NCC were alarmed by its condition.

“You couldn’t build one of those today. They are not acceptable,” Newbury Conservation Commission Chairperson Katheryn Holmes said Friday.

Constructed in 1970, the system relied on evaporation from the lagoons and saturating the spray fields during the non-winter months.

“We probably wouldn’t have been so concerned about the parking lot as much as we were about the lagoons,” Holmes said.

The NCC’s complaint contends that the original design constraints such as yearly capacity and design life, “are not available and likely do not meet today’s standards,” Holmes said, and there is “no end-of-life plan for replacement.”

Russell, of Friends of Mt. Sunapee, was also skeptical about the need for additional parking.

“We can’t support it,” Russell said. “We feel that currently, there is more than enough parking, which is documented in the annual operating plan,” particularly considering access to overflow parking at the beach.

The NCC and other conservation organizations, including the Friends of Mt. Sunapee, are asking Stewart to pause the project until more studies can be done to determine the integrity of the wastewater system and the environmental impacts of the proposed parking lot.

“The commissioner has the authority to put this project on hold until we resolve all these other issues with the sewage treatment facility,” Russell said.

Comments regarding the parking lot project may be sent to Stewart at MountSunapeeComments@dcnr.nh.gov until 4 p.m. on Monday.

Christina Dolan can be reached at cdolan@vnews.com or 603-727-3208.