.....Advertisement.....
.....Advertisement.....

Dam story

-A A +A
By Katy Korkos

 

For more than 70 years there was a reservoir in Los Alamos Canyon, supplying water first to the Ranch School, then to the Manhattan Project and the Los Alamos Scientific Laboratory and eventually to Los Alamos County’s parks and fields. Until the Cerro Grande Fire in 2000 destroyed the surrounding slopes, sending hundreds of thousands cubic yards of debris into the canyon with the first summer rains, the reservoir was enjoyed as a quiet spot for picnics, fishing and hiking.The Pajarito Plateau Watershed Partnership hosted a forum Thursday in Fuller Lodge to get an overview of the future of the once-popular community asset, which has now been closed to public access by the Forest Service.The forum included presentations by Greg Kuyumjian, USDA Forest Service hydrologist, Tim Glasco, Deputy Utilities Manager for Gas, Water, and Sewer Services for Los Alamos Utilities Department, George Lawrence President, Pajarito Mountain Ski Area, and Craig Martin, Open Space Specialist for Los Alamos County.  “The reservoir is a place near and dear to Los Alamos and the community needs a status report on the conditions and future plans for this valuable recreation place,” Martin said.While researching the history of the reservoir, Martin unearthed some documents about its construction, which began purely as a volunteer effort to bring a reliable water supply to the Ranch School in 1928. A small rock wall was built in the canyon, at the upper end of the wide spot where the reservoir later sat. The Ranch School submitted plans for a larger dam to be built, but never completed the project, and it was taken over by the Army. The Army completed it in 1943.Presenters covered topics ranging from the history of the reservoir, sediment deposition in the reservoir since the Cerro Grande Fire, County plans for the reservoir, and Pajarito Mountain's proposal to use water leaving the reservoir at the Ski Hill.The ownership of the reservoir is complicated, with part of the road leading to the reservoir owned by the DOE, part by the forest service. The dam is owned by the County, but sits on Forest Service land. When the reservoir was stocked with fish, those belonged to New Mexico Game and Fish, Martin said.Kuyumjian showed the group graphic evidence that the slopes of the watershed must be recovering, as smaller amounts of sediments are washing down the canyon each successive year. Core samples showed that 8” of sediment had collected in the bottom of the reservoir in the 57 years prior to the Cerro Grande fire, and post-fire, 120” of sediment collected in one year. “We had three feet in one storm,” Kuyumjian said.“The canyon is starting to clean itself up,” Kuyumjian said, adding that the risk of rock falls into the canyon is still very high, especially in the spring. “The highest risk is with lots of moisture, and the freeze-thaw cycle,” he said.Glasco reported on progress the county has made in getting the dam repaired. The county received $1.2 million from Cerro Grande funds to repair the structure, but in 2005, new state regulations classified the dam as “high-hazard,” which will make repairs more expensive. Glasco said that plans to fix the dam by widening the spillway, changing the slope of the dam and stabilizing the embankment to current standards are now under review by the state engineer’s office.“The Department of Public Utilities is currently awaiting approval by the Office of Dam Safety,” Glasco said. “Based on preliminary estimates, costs may exceed available funds.” He said that the preliminary estimates show that it might cost $1.5 million to repair the dam. The department has requested $500,000 from the Water Trust Board.“I believe that council direction was clear in that rebuilding of the LA reservoir is a high priority and that if utilities, Cerro Grande funds, or other directed funding was not sufficient to complete the rebuilding then other sources need to be dedicated. The council can then take that up at a public meeting,” Councilor Mike Wheeler said in a statement earlier in the week.Lawrence presented the ski club’s needs for water use from the watershed to supply water for a reservoir on top of the ski hill to be used for snowmaking. Lawrence said that man-made snow would enable the club to have a reliable ski season if nature doesn’t help, and that most of the water used would return to the watershed when the snow melts, with only about 4 percent lost to evaporation.“Snow-making is essential for the long-term survival of this recreational asset,” Lawrence said. He said that the stream flowing down the canyon was a year-round stream, with a steady stream flow of 50 gallons per minute even in 2006, the driest year on record.The community forum was sponsored by the Pajarito Plateau Watershed Partnership, a regionally based group of citizens and professionals concerned with issues affecting watersheds on the eastern flank of the Jemez Mountains in northern New Mexico including Los Alamos, San Ildefonso Pueblo, Española and the surrounding areas. The group studies issues of water quality, water quantity and erosion.