The Marin Municipal Water District has approved spending up to $1.25 million for environmental review of a proposed pipeline that would boost the county’s supply.

The district board voted unanimously Tuesday to hire Panorama Environmental Inc., a San Francisco firm, to provide environmental compliance and permitting services for the project intended to convey more Sonoma County water to Marin reservoirs.

The “atmospheric river capture” project would tap into an existing aqueduct with a new pipeline.

“I’m super proud of our beginning investment in this massively important project,” said Jed Smith, a district board member.

The approval authorizes the district to hire the company on a base contract of $1.05 million, with optional services costing no more than $198,248.

The pipeline project was selected in February as the district’s priority effort to increase supply. It would be the largest water supply project since Kent Lake was expanded in 1982, according to the district.

In April, the district approved an $9.7 million expenditure on the project design. The contract went to Carollo Engineers, a firm in Walnut Creek.

Lucy Croy, the district’s water quality manager, said it received bids from two environmental consulting firms and found Panorama Environmental to be the right fit. Croy said the district has worked with the company on other projects.

“They demonstrated quite a good awareness of the project and the key areas that we see that will be very important moving forward with a project of this size,” Croy said. “In addition to their technical strength, they also showed quite a bit of adaptability.”

Croy said the environmental compliance work by Panorama will happen in tandem with the design work by Carollo.

The project was derived from the district’s water supply “road map,” a strategy developed in response to the 2020-2021 drought.

About 75% of the Marin Municipal Water District supply comes from the Mount Tamalpais watershed and hills of West Marin. Its seven reservoirs have a combined storage capacity of about 80,000 acre-feet of water. The district serves about 191,000 residents.

The rest of the water comes from the Russian River watershed. Treated water from the river is channeled through an aqueduct along Highway 101 for blending into Marin’s distribution system. Excess water flows into the ocean.

Right now, there is no way to capture that water for later use.

Estimated at $167 million, the proposed project would construct a 13-mile, 36-inch pipeline and a pump station to redirect some of that water into the Nicasio Reservoir for storage. The pipeline could yield 3,800 to 4,750 acre-feet of water a year.

Staff expect the design and environmental review to be completed by early 2027. Construction could begin soon after, and the pipeline could be operational by 2029.

Potential future phases of this project, which would cost more money, could increase replenishment of stored water to up to 8,100 acre-feet, staff said.

District board member Ranjiv Khush asked about the level of environmental review the district can expect from the contract.

Staff said that because of the project size, they expect a full environmental impact report will be needed to meet requirements set by the California Environmental Quality Act.

The contract also leaves room for the potential need for National Environmental Policy Act reporting. The district would need to seek that level of clearance in order to be eligible for federal grants, said Paul Sellier, the water resources director.

“I definitely support moving forward with this and I’m really excited to get this project moving,” board president Matt Samson said.