The Sacramento Bee reported Thursday that the San Juan Water District board of directors approved the move this week.
The district serves more than 265,000 people in the Sacramento suburbs, including the communities of Citrus Heights, Orangevale and Folsom.
Most of its water comes from Folsom Reservoir, which the newspaper says has shrunk perilously low amid one of the driest winters in California history.
District General Manager Shauna Lorance says the call for conservation is not mandatory, but it could become so next month if the area doesn't get rain soon.
The district also is extending a request for a 20 percent cut in all water use that has been in place for months.
A new study says California's four-year drought has reduced hydroelectricity generation, resulting in higher electricity costs to ratepayers and increased greenhouse gas pollution.
Legislation introduced in the California state Assembly would create the Lower American River Conservancy to improve, protect, preserve and possibly expand the 5,000-acre American River Parkway.
January brought above-average rainfall and snow to much of California, partly due to El Niño. But forecasters say the ocean warming condition is "taking a break" for the next week or longer.
The U.S. Drought Monitor says, other than a slight reduction in exceptional drought in the northern Sierra, it needs more time to assess impacts of the recent moisture on California's long-term drought.
California regulators have made modest adjustments to water conservation requirements for cities.