Lyon County approves conditional use permit for methane digesters at Mason Valley dairy

The Lyon County Board of County Commissioners on March 6 approved a conditional use permit for expansion of anaerobic digesters at Desert Hills Dairy in Mason Valley, allowing CEA Dairy RNG Nevada LLC to operate additional methane‑production equipment on an approximately 163‑acre parcel.

County Senior Planner Louis Cariola told the board the digesters had been constructed earlier and used to convert dairy manure to biogas; state law and Nevada Division of Environmental Protection requirements prompted the county to require a conditional use permit after the facilities were already installed. “In 2023, planning staff was contacted by NDEP’s supervisor of their chemical accident prevention program, and we were made aware of the fact that Nevada Revised Statutes require the local jurisdiction to issue a conditional approval for these methane production operations,” Cariola said.

The conditional use permit covers either a third tank (about 1.8 million gallons) or a covered lagoon option (over 35 million gallons) plus dewatering equipment. Cariola and planning staff recommended the tank option; the Planning Commission had forwarded a 6–0 recommendation of approval limited to the tank and asked the applicant to return if they pursued the lagoon.

Public comment focused on local traffic and safety near Campbell Lane and U.S. Highway 95A. Resident Phyllis Hisket said trucks already create hazardous conditions at the Campbell/95A intersection and asked that truck traffic be routed to Feral Lane if possible. “We can sit on our front porch and listen to trucks screeching to that intersection…More truck traffic, I think we’re just asking for fatalities at that intersection,” Hisket said.

Commission discussion emphasized limits on county authority over public roads and the need for safety improvements rather than prohibiting use. Cariola acknowledged odor as a primary concern and said staff had not identified feasible mitigation measures at the staff review level: “I wouldn’t endeavor to say zero odor,” he said, noting the lagoon would have a cover but that some transfer odor is likely.

A commissioner motion to approve the conditional use permit, with the conditions in the staff report, passed unanimously.

The permit requires the applicant to obtain all building permits and any fire‑district reviews that apply; any change to the lagoon option would require returning to the Planning Commission per that body’s recommendation. The file and staff report show the digesters were previously reviewed by county staff in 2020 when the dairy requested authorization to construct two tanks and were treated as accessory to the existing dairy use at that time.

The county record and staff materials note the decision responds to NDEP and state statutory requirements and that the parcel is in a rural residential (RR‑20) zoning designation with an agriculture master‑plan designation.

The board took no additional action on related road improvements; public commenters and commissioners said intersection safety should be addressed through separate road‑safety or traffic engineering work.