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Warm weather’s arrival brings Sierra meltdown concerns

By: Gus Thomson, Journal Staff Writer
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Records show the snow has piled up in the Sierra further into the spring than any other time over the past 65 years. Now it’s time for the meltdown. Just how fast the snowpack lingering long in the mountains will melt is a question on many people’s minds – from whitewater rafters to flood prone lowlanders to the water providers that are trying to balance storage needs with the potential for a warm-up that could spike river flows. Randall Osterhuber, researcher at the Sierra Snow Lab, said that there was more snow on the ground Wednesday at Donner Summit than the location had ever had before. The snow lab, run by UC Berkeley, has records dating back to 1946. Wednesday morning’s measurement showed a 91-inch snowpack depth at 6,900 feet. But that was already dropping as warmer temperatures moved into the region after weeks of cold, snowy weather. Osterhuber said the snowpack depth had lost 5 inches in the previous two days. Normally the snow would have been long gone. May 23 is the average date for the last traces of the white stuff to disappear. “In an average year, we have zero snow depth on June 8,” Osterhuber said. Downstream rivers, including the Middle and North Forks of the American near Auburn, had been flowing fast and cold under rainy skies this spring. Lorraine Hall, business manager of Tributary Whitewater, said Wednesday that rafting companies are hoping for a long, slow rise in temperatures over the next few weeks to avoid a sudden onrush of water. That would mean a season that normally is beginning to shut down on some rivers now that could last through the beginning of July, she said. One of those rivers is the undammed North Fork, which joins at the confluence in the canyon below Auburn with the Middle Fork of the American River. Hall said that because of increased releases brought on by higher water levels, Tributary has been shifting some of its rafting from the South Fork to the more placid Middle Fork. The business has also been taking precautions by putting in age limits on some wilder South Fork runs and ensuring that two rafts rather than one set out at the same time. “You never know what Mother Nature will throw at you,” Hall said. “The weather has been driving us nuts more than the water. But the forecast is for things to stay cooler at the moment.” Placer County Water Agency’s Middle Fork Project of reservoirs, dams and power stations is ready to handle any surge in water from upstream, Director of Strategic Affairs Einar Maisch said. From time to time, one of the projects dams – at Hell Hole or French Meadows reservoirs – will spill over when excess water flows overcome storage capacity. Maisch said the Middle Fork project averages a spill once every 6 to 8 years. While French Meadows reservoir has drawn down by construction on an expanded spillway, Hell Hole is expected to spill, he said. The French Meadows’ L.L. Anderson Dam spill in the 1990s caused significant erosion damage below the structure. But spills normally have no negative impact and are, in fact, a positive event in the life of the river downstream, Maisch said. “It’s good for fisheries and aquatic organisms,” he said. “It stirs things up and moves rocks around. It’s good for the system.” The Folsom Dam is already increasing releases in anticipation of a potential warm-weather surge in snowmelt. The Bureau of Reclamation announced Tuesday that it will increase releases from the dam into the lower American River from 7,000 to 9,000 cubic-feet per second. That could be increased even further to as much as 15,000 cfs. Flows at 10,000 cfs or more could result in some low-lying areas of Discovery Park, Campus Commons and segments of the American River Parkway bike trail being inundated. People participating in recreation along the American River should take appropriate safety precautions during period of high river flows, a bureau release stated. Mark Osweiler, a 96-year-old Auburn resident, said it has been one of the oddest snow years he’s seen in the 29 years he’s lived in the area. “I’ve been over Donner Pass a few times lately and the snow’s still deep on the shady side of the mountain,” Osweiler said. “All the old-timers I know say they’ve never seen anything like it. But that’s Mother Nature.”