With sunny 75-degree days ahead, barbecues hot, picnics packed and that garden ready to till, it’s easy to forget what drought-stricken Sonoma Valley really needs is more rain. As the rainy season wraps up, water officials are planning how to manage water for the rest of this dry year.
On April 7, the Sonoma County Water Agency met with its water contractors from throughout the region, including the City of Sonoma and Valley of the Moon Water District, to provide an update on current reservoir conditions in Lake Sonoma and Lake Mendocino, and to determine what efforts need to be made to conserve during the ongoing statewide drought.
SCWA spokeswoman Ann DuBay said the agency and water contractors determined that, although the drought remains, mandatory rationing “does not appear to be on the horizon” for Lake Sonoma users. In Sonoma Valley, a majority of the water supply comes from that water-agency managed reservoir. DuBay said contractors using this supply would continue with voluntary 20 percent water conservation as requested by Gov. Jerry Brown earlier this year.
Winter rains, especially those in February, have made a significant impact on water storage levels, SCWA spokesman Brad Sherwood said. February 2014, he noted, was the 13th wettest February on record and water storage levels and rainfall have surpassed those during the benchmark 1977 drought year.
The outlook for the water agency’s Lake Mendocino reservoir, which is much smaller than that at Lake Sonoma to begin with, is less positive, DuBay said. The Ukiah region is still facing one of the driest years on record and areas that rely on water from Lake Mendocino and the upper Russian River, from Healdsburg and above, will continue with the mandatory conservation efforts already in place as issued through their water contractors.
Rainfall in Ukiah is at 47 percent of its average, while it is at 62 percent of average in the Santa Rosa area, DuBay said.
The lower Russian River water supply system, DuBay said, moved from a “critical” designation to a “dry” designation, based on storage thresholds approved by the State Water Resources Control Board’s recent order approving a change to how SCWA measures water supply levels in the reservoirs. The upper river supply conditions remain critical.
DuBay said a technical advisory group for water contractors meets monthly to stay abreast of supply levels and determine the appropriate courses of action during the drought.
Weather predictions for later this year may indicate wet conditions. Earlier this spring, the National Oceanic and Atmospheric Administration issued an official El Nino watch. While forecasts show possibilities of very wet weather, SCWA Chief Engineer Jay Jasperse said stringent water management until that wet weather hits, which is usually in the latter part of the year, is especially crucial.
Once every few years, he explained, a warming of the central Pacific occurs, from a combination of wind and waves in the tropics, to form an El Nino. Early signs of El Nino are already appearing hundreds of feet below the ocean’s surface, according to NOAA reports, but an official El Nino season will not be declared until later this year. El Ninos are usually strongest from December to April.
In 2012, the last time El Nino appeared, El Nino temperatures were present in the early part of the year and later shut down.
“We will believe it is an El Nino year when it starts raining because the price for misjudging that is significant,” Jasperse said.
The flip side of El Nino is called La Nina and has a general cooling effect. It has been much more frequent than El Ninos lately, with five La Ninas in the past nine years.
“Like everything with weather, there is no guarantee,” Jasperse said. “From a water manager perspective, we have to play pretty conservative.”
Jasperse explained recent weather patterns, and those since the 1990s, have been influenced by a temperature difference between the northern part of the equator and the Gulf of Alaska, with a jet stream that swings up north. This pattern, he said, gives way to El Nino and La Nina years.
One of the biggest areas of focus for Jasperse and his team is predicting the size, location and duration of atmospheric rivers, which are bands of water from storm systems that undulate throughout the atmosphere like rivers. Atmospheric rivers, Jasperse explained, make up close to 50 percent of the region’s rainfall and are responsible for 80 percent of the floods in the Russian River system.
Currently, SCWA is partnered with NOAA’s Office of Atmospheric Research and the National Weather Service and Scripps Institute.
With a better understanding of where these bands of water will hit and when, Jasperse said, water managers will be able to make better decisions about releasing water for flood control and storing water for droughts.
The heavy rain in February, according to Jasperse, was the first atmospheric river to hit the Valley in 14 months.
The research teams are most skilled at predicting when atmospheric rivers will not come, less-skilled at predicting when they will come, and least skilled in predicting where they will hit. The teams are still working to determine the intensity and duration of the rivers.
“These atmospheric rivers are what we have to design our systems around, in terms of flood control and drought management,” Jasperse said. “Our actual understanding of predicting weather is improving, so, maybe we don’t have to release water for flood control if we know that there isn’t going to be any rain.”
Japserse noted that while climate models vary, with some research indicating wetter years to come and others indicating drier years, they all agree it will get warmer and more unpredictable. Warmer weather, he said, increases the demands for water and is a key factor in managing water supply. A theory among researchers for the region, he said, is that the variability is likely caused by the greater role of atmospheric rivers.
Lake Sonoma, Sherwood said, has enough water to sustain water consumers for several years, but is still below its 90-percent springtime average capacity. And, he added, storage capacity percentages are deceptive in the spring because the amount of water allowed for storage is increased during this time. The agency works with the United States Army Corps of Engineers (USACE) to manage both of its reservoirs, and follows a plan made more than 50 years ago for their flood control. With ecological factors and species protections in place, Sherwood said the way in which the agency manages water has changed significantly, resulting in lower flows. The manual for USACE is governed by Congress. Rep. Jared Huffman, D-San Rafael, has introduced a bill to allow USACE to update their practices based on new conditions and atmospheric river data.
Looking ahead, Japserse said the agency is forecasting very low storage levels in Lake Mendocino this summer and fall, while the much larger and more resilient Lake Sonoma is in better condition, with several years of supply. However, declining groundwater levels in southern Sonoma Valley have become an increasing concern and factor in the demand for reservoir water.
The key to surviving this drought, according to Jasperse and many other water officials, is conservation.
City of Sonoma Engineer and Department of Public Works Director Dan Takasugi said the city is still asking water users for a 20 percent water usage reduction and is actively working to promote conservation through leak detection and water-saving programs. Takasugi explained the city is “aggressively” pursuing water leak detection, water waste enforcement and monitoring remote fire hydrants for water theft. Valley of the Moon Water District has a similar program and offers incentives and rebates for conservation.
The water agency is teamed with the City of Sonoma to supply water-saving kits at the Wednesday, April 23, Drought Drive-Up. The event, which runs from 7:30 a.m. to 6:30 p.m., will be held at the Arnold Field parking lot off First Street East, near Blue Wing Drive. Kits include efficient showerheads, faucet aerators and dye tablets to detect toilet leaks. Any residents, regardless of their water provider, are welcome to pick up a free kit. Water-saving kits can also be picked up at Valley of the Moon Water Districts office, 19039 Bay St., Sonoma.
Takasugi said, as of Monday afternoon, staff were still looking for volunteers for the event. Any interested volunteers should contact Public Works at 938-3332.
Information about the drought, water conservation tips and the Drought Drive-Up can be found at savingwaterpartnership.org.