Drought Conditions Improve In California, Nevada

The lastest drought update shows that as California moves toward the dry summer months, conditions continue to improve.

Improvement comes as the California State Water Resources Control Board ended mandatory statewide water conservation regulations. The new regulations allow local water districts to set their conservation targets based on their ability to meet demand if there are three more severely dry years. The water agencies will submit their level of supply to the state water board.

The U.S. Drought Center says the past week brought "widespread improvements" in drought conditions in northern California and Nevada.

The Drought Center measures the intensity of drought.

The percentage of improvement in California (before the weekly Tuesday morning cutoff) show a nine-percent reduction in the level of severe (63.5 percent) and a five-percent reduction in extreme (42.9 percent) drought. In February 2016, extreme drought covered 61 percent of the state.

But 94.5 percent of California remains abnormally dry, with 86 percent in moderate drought. Exceptional drought is 21 percent this week.

"On this week’s map, widespread one-category improvements were made across northern California and northwestern Nevada where conditions have steadily improved since the beginning of the Water Year (October 1)," according to the report released May 19. "In the northern Sierra, spring rains combined with a generally above-average snowpack have led to considerable increases in reservoir storage levels in area reservoirs."

But the U.S. Drought Monitor report also says that "below normal" reservoir storage levels remain in California, Nevada, Arizona and New Mexico, citing the Natural Resources Conservation Service.

The May 18 reservoir update from the California Department of Water Resources shows that Lake Oroville is at 115 percent of its historical average (and 96 percent of capacity), while Shasta Reservoir is at 107 percent and Folsom Lake is 108 percent of historical average.

But winter 2015-16 brought a north-south split in precipitation that favored the north over the south. As a consequence, conditions did not improve equally in California.

"In southern California, precipitation accumulations since the beginning of the Water Year have been below-normal, especially in coastal areas of Los Angeles, Orange, and Ventura counties where the percentage of normal precipitation is less than 50 percent for the Water Year," the weekly report notes.

The statewide Sierra Nevada snowpack was 33 percent of normal as of May 18.

The three-month U.S. Seasonal Drought Outlook, released May 19 from the NOAA/NWS Climate Prediction Center, shows drought persists in California, western Nevada and southwest Arizona through August 31. 

Extreme Drought Declines In Nevada

Conditions in northwestern Nevada have improved significantly as extreme drought was reduced from 23 percent to 5.3 percent.

"A one-category improvement in a large area of Extreme Drought (D3) was made in response to a combination of short-and long-term indicators supporting improvements including:  snowpack conditions, stream flows, reservoir storage levels, percentage of normal precipitation, and vegetative health," says the report.

While conditions improved in California and Nevada, conditions declined in Oregon and Washington.

"In the Pacific Northwest, a combination of short-term precipitation deficits (30-day) and above-normal temperatures led to the introduction of an area of Abnormally Dry (D0) in northwestern Oregon and western Washington where stream flow (28-day average) activity and soil moisture conditions are below-normal in many locations," the U.S. Drought Center reports.