Drought Forecast

February 25, 2018 by Fred Allebach

I’m always taken aback by how many people are at the car washes on Hwy 12. Like turf yards, the compulsively clean car seems like a bad, water wasting habit that has become normal and accepted. This is a habit that needs to be broken in a state where the governor has called for “conserving water as a way of life.”

Guess what? It looks like drought is back in So Cal and on the way in Nor Cal. Time for the Sonoma County Water Agency, Valley of the Moon Water District and the City of Sonoma to take some proactive measures to begin conserving the common pool of water up in Lake Sonoma and Lake Mendocino.

A Feb 20^th P-D article says, “In the Northern Sierra Nevada, the winter so far has been the third-driest on record for the year’s wettest three months — December, January and February — produced very little rainfall, said John Leahigh of the California Department of Water Resources.

“The water content of the Sierra snowpack, which feeds water supplies, is about 20 percent of normal for this time of year, he said.

“Most of California’s reservoirs are at or slightly above their historical average for this time of year, but experts expect that to fall when water is released in the spring and summer and not enough melting snow can replenish it.

“This is a very ugly picture in terms of the water supply management,” Leahigh said. Keep in mind for us in Sonoma County, that the state’s water supply picture has a larger lens than just the Sierra Nevada-dependent reservoir and delivery system.

Drought on the horizon is confirmed by a KQED report, that “according to the U.S. Drought Monitor, almost half the state is experiencing at least a “moderate drought.” More than 91 percent of the state, including the Bay Area, is at least “abnormally dry,” the stepping stone to drought.” Since the bulk of Nor Cal rains fall by the end of February, our abnormally dry could tip to drought rather quickly.

The following is the NOAA long term forecast: “In the West, drought intensified the past 30 days (from the south-central Plains)across the Four Corners Region, the Great Basin, and in California and Oregon. The Water Year to Date (WYTD) has been exceptionally dry and mild across the southern half of the West (particularly in the Southwest), with basin average precipitation ranging from 5-70% of normal, and basin average snow water content (SWC) even lower (between 0-50%) as of February 14. With California’s wet season typically ending in April, time is running out for bringing the state’s WYTD totals close to normal. With cold and dry weather expected in the short-term (QPF and ERFs), and above-normal temperatures and sub-median precipitation expected in southern sections during March and MAM (with the opposite in northern areas), the outlooks favor continued deterioration and expansion of drought through May in the Southwest, California, and the Great Basin. Oregon is in the EC precipitation area, so it is possible for enough precipitation to occur to bring the state out of D1 by May. The northern edge of the drought (basically I-80) in the West marks the boundary between above- (north) and below-median (south) precipitation odds in the LLFs, thus this northern drought boundary will stay where it currently exists. Forecast confidence for the West is high except in Oregon where confidence is moderate.”

A NewsDeeply forecast says, “For California, La Niña creates unique challenges. Its impacts are usually sharply different on either side of a line crossing the middle of the state, causing dry conditions to the South and wet conditions to the North. Often this line falls near Interstate 80, which crosses the Sierra Nevada from West to East near Lake Tahoe. But it can shift and swing, depending on a variety of factors, such as atmospheric rivers.”

“The impacts of La Niña can be very different from event to event in Northern California,” Okumura said. “According to my study, this winter the precipitation will be reduced across the whole state of California.”

Nor Cal could avoid slipping into drought, as the line for wetter weather in a La Niña year is right in our back yard, however, we’re running out of time to field the rain. It looks like some pulses of rain and showers are coming next week.

The water delivery system here in Sonoma County is different from the bulk of the state, which is contingent on Sierra snowpack. The Russian River is the basis for nearly all Sonoma County municipal water use, and some in Marin County as well. The conditions that supply the reservoir and delivery system here can maybe tip in our favor while the rest of the state suffers a different fate.

Regionally, groundwater is a whole different ballgame than Russian River water. Sonoma County has three at-risk groundwater basins that come under management by Groundwater Sustainability Agencies mandated by the state Sustainable Groundwater Management Act. Approximately 50% of groundwater in the Sonoma basin is used by agriculture and 30% by rural residential users. In times of drought when surface water and rains proved less cushion, groundwater use goes up, and the finite supply in the deep aquifer system is then depleted, possibly permanently.

Groundwater is a resource that can only be managed if there is some way to recharge it. Rains recharge the surface aquifer system. For deep aquifer systems, minus well-injection recharge, management amounts to how quickly or slowly the resource will be used up permanently. Using deep aquifer water without a recharge off-set is kind of like spending your principal.

The upshot: California is a state prone to drought. The effects of human-caused climate change alone, have a good possibility of creating drier, warmer weather. California is a geographic area prone to cycles of drought in the last 10,000 years. The state may be entering a double-whammy drier and warmer period, one cyclical, one human-caused. See points three and four of the conclusion, p.158, from the link above.

My advice for water managers would be to get ready to put out a voluntary conservation notice soon. Start to prime the public with an initial conservation signal. If by mid-March the forecast looks dry, get ready to move back into drought mode and hit 25% conservation measures quickly. Also, allow any current rains in March to fill reservoirs into the flood control pool, if the Army Corps and NOAA forecasts can allow it. If water ends up costing more, so be it, water should cost more in a place where it is fundamentally precious.

A certain amount of basic household use water can be provided to customers at an affordable rate under the state’s human right to water law.

What can you do? The bulk of people’s personal water use goes to landscape irrigation. This is where a lot of savings can be had. Two things we can all do: get rid of turf and high water use landscape irrigation and move to non-irrigated xeriscape, and wash the car only once or twice a year. For car washing, let’s change the channel and make it a status marker of who has the dirtiest looking car!

Another thought is that since cannabis is a very high water use crop, land use decision makers should only allow it to be grown in areas that have a decent, guaranteed water supply, and not a supply that will diminish groundwater, i.e. cannabis needs to be grown in Humboldt and Del Norte counties and coastal Oregon, not in drought-prone areas of California.  The state already has enough trouble with entitled-feeling high water use, high value crops like almonds.

A final thing to do is to create legislation that undoes the San Juan Capistrano judicial ruling, and that allows tiered water rates so that profligate users can be hit hard in the pocketbook.

This essay constitutes a notice to be alert for a drought signal. I hope I’m wrong. I also hope that water managers will not dilly dally too long if water conservation is really to be our way of life.