Facing a drought that everyone is calling unprecedented, Marin County is tightening its water-use restrictions in ways that other counties may soon follow.

Marin was the first county in the Bay Area to impose some water-use rules that took effect May 1, and those included no washing of cars at home, no refilling of pools, and limits on irrigation.

On Wednesday, the Marin Municipal Water District (MMWD) announced new restrictions that go further with irrigation — limiting everyone to the use of sprinklers just once a week on a designated day, with each town and city assigned to one weekday to ease enforcement. Drip irrigation is now limited to two days per week.

Also, residents can't power-wash homes or hose down driveways, or flood gutters.

"We typically see residential water demand double during the summer months, which is primarily due to lawn irrigation,” said Larry Russell, Ph.D., vice president of the district’s board of directors, in a statement to KRON4. “This drought is unprecedented and we’re asking all of our customers to use as little water as they can. These new irrigation restrictions are designed to enable us reach our collective districtwide goal of reducing water use by 40 percent."

As the district explained in April, Marin relies on reservoirs in the coastal range for much of its water, and these started the year at low levels.

San Francisco is less likely to see mandatory restrictions this year, due to ample resources coming from the Hetch Hetchy reservoir, and the city's comparatively low water use. As SFist noted in May, for the last year for which data is available, 2016, the city used the least water per capita in the region that year, largely due to the relatively low number of residential lawns.

Most of our region is now in the highest level of drought, called "Exceptional," according to the U.S. Drought Monitor.

Last month, the Santa Clara Valley Water District board imposed light restrictions on residents there, limiting lawn watering to three days per week, and banning the private washing of cars and boats. The district is currently aiming to decrease overall water use by 15%.

Photo: Paul Moody