Customers of San Juan Water District in are being asked to reduce their water use 5 to 10 percent due to concerns that Folsom Lake may not be able to serve normal demand.

The district’s board of directors last week adopted a Stage 2 Water Alert, which calls on customers to take voluntary actions to conserve water. The district serves Granite Bay and portions of Roseville, Folsom and Orangevale.

“We’re encouraging residents to avoid all unnecessary and wasteful uses of water,” Judy Johnson, the district’s customer services manager, said in a statement.

The request comes after the driest January-through-June period in the northern Sierra Nevada region in history. Lack of snowfall and resulting poor runoff has left many California reservoirs in a depleted state, including Folsom Lake. The lake supplies most of the water used by San Juan customers, and there is mounting concern it will not be able to meet demand next year.