Editorial: Routine, cautious looks at desalination make sense for Marin

While interest and investment in desalination has grown, MMWD’s latest consideration doesn’t mean the district is embarking on its third costly foray into embracing the technology.

When voters in the Marin Municipal Water District elected three new board members – ousting two incumbents after another had retired from the panel – they came aboard with a promise to take a fresh look at the options and opportunities to bolster the resilience of the local water supply.

The election and change came in the wake of the district’s 2020 alarming warning that even with strict conservation measures the prolonged drought risked, within months, draining MMWD’s supply.

Then it rained. But the threat was too close for comfort for most voters.

Some voters decried MMWD’s 2010 decision to put its controversial desalination plant plans on the political backburner after spending millions on a trial plant on San Rafael Bay. The board, at the time, opted to bank on conservation, encouraged by MMWD customers’ efforts to reduce water use.

It was the second time since the 1976-77 drought that MMWD had seriously pursued building a desalination plant to expand the district’s supply and help it weather a prolonged drought.

The biggest challenge is cost, not only to build, but to operate.

That’s why the proposal to join forces with other North Bay water agencies to build a plant on the Petaluma River sounded encouraging. Sharing those costs could save money and address that challenge.

It would be a regional solution to protect against a regional crisis.

The district also faces another challenge – politics.

A 2010 ballot measure would require MMWD to seek voter approval for funding and building a desalination plant.

That wasn’t a rejection of the idea, but it is a political hurdle.

Since then, there have been advances in desalination, both technically and politically.

Last year, Gov. Gavin Newsom announced that desalination would be part of the state’s drought protection strategy and steered $5 million to three projects, including one in Mendocino. They were the latest in the state’s nearly $100 million investment in desalination projects up and down the state.

In 2022, Carlsbad touted its desalination plant – and its 50 million gallons per day production – as a shield protecting the San Diego area from drought.

While interest and investment in desalination has grown, MMWD’s latest consideration doesn’t mean the district is embarking on its third costly foray into embracing the technology.

At a recent meeting, some board members cringed at the cost – $273 million to $401 million for construction and as much as $30 million per year to run.

Both would probably mean increasing rates.

To their credit, they have focused on other water-saving options, as well. They may not offer the seemingly bottomless design of desal, but they are a lot less expensive in both construction and operation.

Increasing the capacity of MMWD’s seven reservoirs and instilling supply-efficient operating measures make sense.

Still, desalination should be considered a possible option, especially as MMWD weighs the ramifications of growth in local population and businesses.

It may also make sense in the future if the local water supply returns to perilously low levels. Or, if state and federal funding significantly brings down the cost.

Routinely taking a hard look at desalination is the right strategy, but directors, at this time, should remain cautious.