As the Delta Stewardship Council wraps up completion of the Delta Plan and transitions to putting it into action, the El Dorado County Water Agency invited council scientists to view the geography of El Dorado County waters that flow into the Delta.
A tour was held on Aug. 29, starting at the County Water Agency offices. General Manager Dave Eggerton said there have been a lot of scientific studies on conditions in the Delta, and recently there have been studies in El Dorado County on the relationship between forest and water management, different methods of ensuring water storage, and creating a water information system. “The results of these studies will benefit water reliability for the state of California, as well as El Dorado County,” said Eggerton.
Lessons from Angora Fire
South Lake Tahoe is not normally included in American River watershed discussions, but important lessons are being learned about forest fires near residential neighborhoods from the restoration studies that were conducted after the fire.
Standing on a newly paved road lined with recently built homes facing the steep mountainside site of the Angora Fire, guests listened to South Lake Tahoe Public Utility District Assistant Manager Paul Sciuto describe the fire and the district’s response in the aftermath.
High winds whipped up an unattended campfire on June 24, 2007, in the Angora Creek watershed flanking the west side of the city of South Lake Tahoe . By the time it was contained on July 2, the fire had burned 3,100 acres of Jeffrey Pine and mixed conifer forest and destroyed 254 homes. Previously, fire treatment was done on 480 acres. Trees were thinned and fuel loads reduced. These areas had the least amount of damage. The U.S. Forest Service pegged the final loss plus the cost of suppression at $160 million.
The effects on the Upper Truckee River and Lake Tahoe were minimal. However, downstream, in Angora Creek, nutrient and sediment concentrations increased markedly in the two dry years following the fire.
After an intense forest fire, the soil develops a hard surface and loses its ability to store water. Sediment material, an accumulation of soil, rock and sand, is carried by wind and rain into waterways, where it sinks to the bottom. Sediment carries nutrients.
Excess nutrients in the water stimulate an overabundance of different types of plant growth, crowding out some of the growth that fish depend upon, lowering oxygen levels and reducing the amount of surface water.
The process is called eutrophication, and Angora Creek had a bad case. Excess runoff resulted in significant increases in five measured nutrients in 2008-09. For example, nitrate concentrations were measured up 8.5-fold.
Advances in water management
At the South Tahoe Public Utility District office, Roger Bales, Ph.D., professor of engineering and director of the Sierra Nevada Research Institute at UC Merced, gave an update of the snowpack sampling he and his team are doing in the American River watershed.
Our present system of measuring snowmelt by sticking a pole in the snow and determining water content will not be adequate in the future, said Bales. “A modern, accurate water-information system is critical for water security, especially given the changes brought about by climate warming in the mountains.”
Bales and team started their research in a two-square-mile area near Shaver Lake in Fresno County. In 2011 the National Science Foundation awarded a $2 million grant to the institute to develop its prototype in a 2,000-square-mile area in the American River basin. Satellites collect data from ground monitoring recorded by tiny sensors. The system uses a network of matchbook-sized wireless sensors to track snowpack depth, water storage in soil, stream flow and water use by vegetation.
The research also involves forest management. Bales said the object is to get the snow to the ground and stay there until spring, essentially providing a massive natural refrigeration unit that thaws slowly and releases water gradually as the need for water increases in the summer.
For optimum water management, the team’s work points to thinning out tree stands that create dense canopies. The roof-like canopies prevent snow from reaching the ground. On the other hand, when trees are too far apart, heat from the sun will melt the snow quickly, causing an early runoff.
Bales said that if we can reduce the uncertainty in water forecasting, we could possibly add tens to hundreds of million dollars to the state’s economy.
The research is in the early stages. As it develops, the information should be made available to water managers, farmers, flood-control managers, scientists, hydroelectric managers, recreation managers and others who could benefit. Bales said he is applying for an additional $15 million grant from the National Science Foundation to continue advancing the Intelligent Water Information System throughout the Sierra Nevada.
Diversion canal critical component of mountain water delivery system
When the waters from four high mountain lakes flow into the American River, they are diverted into a canal south of Highway 50 at a point 1.5 miles west of Kyburz, a fall of 3,000 to 4,000 feet. From the diversion point, at about 3,910 feet elevation, a dam channels the South Fork of the American River into the El Dorado Canal. The El Dorado Canal drops another 200 feet along its 22.3-mile length of flumes, tunnels, canals and siphons along steep slopes to the El Dorado Forebay just north of Pollock Pines. A drop of water entering the diversion canal would arrive at the forebay 14 hours later.
The diversion canal at Kyburz is part of Project 184, which was transferred from PG&E to EID in 1999. EID received a 40-year FERC license in 2002.
The forebay regulates water that is delivered to El Dorado Powerhouse and to a water treatment plant.
EID Water-Hydro Engineering Manager Cindy Megerdigian conducted the tour members over the river via a pedestrian suspension bridge to view the water entering the canal and explained how the flows are managed.
Cleveland Fire — 21 years later
The Cleveland Fire was seven times the size of the Angora fire. From Sept. 29 to Oct. 14, 1992, it burned more than 22,000 acres east of White Hall on a steep, south-facing slope next to Highway 50. Two pilots in a fire-retardant tanker plane died when the plane crashed.
Forty-one dwellings were lost and wildlife habitat was destroyed. Highway 50 was closed for several weeks, resulting in economic losses on the western slope and in the South Lake Tahoe area. The El Dorado Canal was severely damaged.
Although restoration work started soon after the fire, five years later a massive landslide of traveled swiftly downslope from the south side of the river at Randall Tract to the north side, burying Highway 50 under 75 feet of mud about 800 feet wider. Again, Highway 50 was closed, this time for 27 days.
The tour group gathered at the Cleveland Corral Visitors Center to view the changes in the burn site. As the group surveyed the many shades of green surrounding them, Mark Egbert, district manager of the El Dorado County and Georgetown Divide Resource Conservation districts, described the scene 20 years ago as scene was completely black and charred. He said the U.S. Forest Service, Sierra Pacific Industries, and other agencies have all been involved in preventing a repeat fire. If we are going to use low intensity fires as a management tool, we have to use it over broad areas and be able to use it continuously over time because high-intensity fires like the Cleveland travel so fast and are so hot they take out everything, he said.
Now there are three different types of landscape. Stands of tall trees that had survived the burn because the fuel loads on the ground had been reduced and the stands treated with repeated low-intensity fires. Another type of landscape was burned and left unmanaged. Two decades after the fire, it holds mostly shrubs, with a few oaks and firs. The third type was areas that had burned, but were replanted and the shrubs controlled to give the seedlings room to grow. Some of the trees in these stands are 30 feet tall. These stands will continue to be treated with low-intensity fires, and should grow into healthy forests in the future.
Gwyn-Mohr Tully, water law specialist, co-founded Tully & Young, Inc., of Sacramento, with engineer Greg Young. The firm integrates legal, technical, political and economic elements of water resource planning.
Tully put the tour into perspective. “We are all connected, whether we want to be or not,” he said. These studies are absolutely critical. Things that happen up here translate throughout the entire system, impacting the fish at the regional level, with effects that are global.
Delta Stewardship Council Lead Scientist Peter Goodwin, Ph.D, summarized the DSC science team’s response. Goodwin came from the University of Idaho, where he was the DeVlieg Presidential Professor in Ecohydraulics and professor of civil engineering, and founder and director of the Center of Ecohydraulics Research.
Goodwin is responsible for providing the best possible scientific information for water and environmental decision-making in the Bay-Delta system. “What we want to do is avoid combat science,” he said, referring to the use of scientists and scientific studies to support political, organizational or personal agendas. His responsibilities include synthesizing scientific information across disciplines, providing independent scientific peer reviews, directing a fellowship program, coordinating with state, federal and local agencies to promote science-based adaptive management, and communicating scientific information to decision-makers, scientists and the public.
He said that visiting the areas that are the sources of the water that flow into the Delta and seeing how the data are developed in the studies being done is important to the DSC scientists’ understanding of the entire system.
DSC scientists who accompanied Goodwin on the tour were: Deputy Executive Officer, Science, Rainer Hoenicke; Environmental Scientist Joanne Vinton; and Program Manager, Delta Science Program Marina Brand. Brand said she and the other DSC scientists are aware of the connection between the mountain watershed and the Delta, but it’s good to get an on-the-ground look at conditions.
DSC Executive Officer Chris Knopp, who retired from the U.S. Forest Service, said part of his job is getting out of the office, visiting other parts of California, and meeting people who are involved in water issues that affect the Delta Plan.