Environmental

Marin Municipal Water District: Reservoir outlook improving
By TortLawNewsOn Dec 6, 2021

The Marin Municipal Water District will likely avoid depleting its main reservoir supplies next summer, according to new projections following last week’s heavy rain.

But the county is not in the clear yet, with local supplies still well below normal for this time of year, officials said this week.

As such, plans will proceed for emergency water supply projects such as a proposed $90 million, 8-mile pipeline across the Richmond-San Rafael Bridge that would pump in purchased Central Valley water.

“Absolutely the rain that we’ve received did relieve a bit of the pressure in terms of the hard deadline,” said Ben Horenstein, the water district’s general manager. “On the other hand, we need this rain to continue and the weather as we all know has been very volatile.

“You can’t just look at the start of the rain season. It unfortunately doesn’t help you predict how the rest of the season is going to be,” he said. “Right now it’s staying the course and continuing to monitor the weather, the rainfall, the benefits to storage and making decisions accordingly as we see things play out.”

For months, the district was projecting that it could deplete supplies in its seven local reservoirs as soon as July or August in the event of a third consecutive dry winter. The reservoirs make up 75% of the water supply for 191,000 people in central and southern Marin.

However, the last week of October dumped more than 18 inches of rain on Marin, which caused reservoir supplies to increase from less than a third of capacity to 52% of capacity in a matter of days.

Additionally, the state recently approved the district’s petition to reduce dam water releases into Lagunitas Creek this winter meant to benefit endangered fish. This is expected to retain about 2,000 acre-feet of water, or about 5% of the existing reservoir supplies, according to district water quality manager Lucy Croy.

As a result, the district projects reservoir supplies will last at least through the end of 2022 if residents continue conservation levels of at least 20%. Current projections show the district would end 2022 at about 20,000 acre-feet of supply, or about 25% of capacity, in case of a dry winter that produces only 25% of average runoff into reservoirs.

Marin Municipal Water District reservoir storage projections as of Nov. 2, 2021. (Credit: MMWD)

While this is good news compared to what was being projected before, reservoirs are typically 66% full at this time of year.

“We’re about 10,000 acre-feet less than we were last year,” Larry Bragman, a district board member, said at the board meeting on Tuesday. “So for sure, the drought is not over. To me, that number really says it all. We cannot be forgetting about what we’ve just gone through because we’re not done.”

Efforts to plan for the proposed Richmond-San Rafael Bridge water pipeline are ongoing.

The district already authorized spending more than $23 million last month to buy necessary supplies and facilities to build the pipeline, which would extend from Richmond into San Rafael via the underside of the top deck of the bridge. A construction contract of around $40 million for the pipeline could come before the district in January.

While the pressure has been lessened by the new supply forecasts, the pipeline still faces many hurdles.

The project requires permits and approvals from a variety of federal, state and local agencies including the U.S. Bureau of Reclamation, the state Water Resources Control Board, the Federal Highway Administration, the cities of Richmond and San Rafael, Caltrans and the East Bay Municipal Utility District.

Diagram depicting how water from the Central Valley could be conveyed to Marin County via a Richmond-San Rafael Bridge water pipeline. (Credit: Marin Municipal Water District)

Paul Sellier, operations director of the Marin Municipal Water District, told the board that the district has begun “intense outreach efforts” in Richmond after residents and Mayor Tom Butt raised concerns about the project’s impacts to their community and the district’s lack of communication.

The district board also voted to authorize a permit application to the San Francisco Bay Conservation and Development Commission that would allow the pipeline work on the bridge to take place.

The district has yet to bring forward a proposal for water purchases, though staff said there have been promising talks with the Glenn-Colusa Irrigation District and the Yuba Water Agency.

Local environmental groups such as the North Coast Rivers Alliance and the Watershed Alliance of Marin have also challenged the water district’s stance that the pipeline would be exempt from state environmental review because it is an emergency project.