CASITAS DAM RETROFIT PLANNED.Byline: Michael Coit Daily News Staff Writer Rising within the steep canyon walls above Coyote Creek is a sentinel to California's dam building era, an earth-filled structure that holds some 250,000 acre-feet of water for residents and farmers in western Ventura County. Casitas Dam Casitas Dam is a dam on Coyote Creek that forms Lake Casitas near Ojai, California. The dam is located two miles above the junction of Coyote Creek and the Ventura River. Water from the Ventura River is diverted to Lake Casitas as well. , located between Ventura and Ojai, was completed in 1959 by the U.S. Bureau of Reclamation. The dam has held firm, carrying flood waters down its spillway spillway, n a channel or passageway through which food escapes from the occlusal surfaces of the teeth during mastication. The occlusal, developmental, and supplemental grooves, as well as the incisal, occlusal, labial, buccal, and lingual embrasures, on eight occasions, with the greatest volume coming from early February through late June following the El Nino-spawned winter rains. Yet the dam is vulnerable. A recent federal study reported that Casitas Dam is located in an area of very high seismic activity, and the greatest threat is posed by a thrust fault visible on Red Mountain less than two miles to the west. Geotechnical investigations completed as part of the bureau's safety program found that the dam's foundation - a combination of upper sand and lower gravel layers - could liquefy liquefy /liq·ue·fy/ (lik´wi-fi) to become or cause to become liquid. during strong ground shaking, allowing the embankment to slump and crack and the reservoir to release. ``It's a highly engineered, well compacted embankment. The problem when this one was built is there wasn't the information on liquefaction liquefaction, change of a substance from the solid or the gaseous state to the liquid state. Since the different states of matter correspond to different amounts of energy of the molecules making up the substance, energy in the form of heat must either be supplied to of sand and gravels that there is today,'' said Bill Pennington, the bureau's dam safety engineer for a retrofit ret·ro·fit v. ret·ro·fit·ted or ret·ro·fit, ret·ro·fit·ting, ret·ro·fits v.tr. 1. To provide (a jet, automobile, computer, or factory, for example) with parts, devices, or equipment not in project in the works. ``The odds are not good there. That's why we want to fix it.'' The fix features three elements: Excavating and replacing the foundation downstream with more compacted earth; constructing a berm berm: see beach. over the treated foundation; widening the dam crest to protect against breaching, which includes a sand filter and synthetic material to hold the dam as water flows through. Pennington said the bureau expects to publish a final Environmental Assessment by the end of this month. $Work to begin in April The time line calls for work to begin in April and conclude by September 2000, with a break for that winter's rainy season. A simliar retrofit already is under way on the dam that creates Lake Cachuma Lake Cachuma is a lake located in central Santa Barbara County, California on the Santa Ynez River. It is formed by Bradbury Dam, a 201 foot (61 m) earth-fill dam built by the U.S. Bureau of Reclamation in 1953. in neighboring Santa Barbara Santa Barbara (săn'tə bär`brə, –bərə), city (1990 pop. 85,571), seat of Santa Barbara co., S Calif., on the Pacific Ocean; inc. 1850. County. But the Casitas Dam project could be delayed a year or more if opposition surfaces and succeeds in gaining a more comprehensive environmental review. Casitas Municipal Water District officials are concerned the bureau will lower the lake level too far during construction, affecting the agency's service to 60,000 residents, businesses and farmers in western Ventura County. Such a loss might be a significant environmental impact that needs further review, the officials said. ``The loss of water is always a concern,'' said Jim Word, a district board member. ``If this happened three or four years ago, after the drought when the lake was so low, I would assume there would have been some rationing,'' he said. ``And they keep projecting that we will go back into (a drought).'' Pennington acknowledged that bureau estimates for lowering the lake 10 feet or more stunned stun tr.v. stunned, stun·ning, stuns 1. To daze or render senseless, by or as if by a blow. 2. To overwhelm or daze with a loud noise. 3. the district. ``We just wanted to give people an order of magnitude A change in quantity or volume as measured by the decimal point. For example, from tens to hundreds is one order of magnitude. Tens to thousands is two orders of magnitude; tens to millions is three orders of magnitude, etc. so it was out there,'' Pennington said. ``It will probably be a very minimal need and it will probably be accommodated for by their normal use.'' Pennington, though, said the bureau ``will never compromise the safety of that dam'' during the project. ``We have had restricted reservoirs in this state and we will do it again if we felt it was necessary.'' Casitas Dam is owned by the federal government. The district owns the water rights and water stored in the lake. The project is expected to cost $20 million. Pennington said there is federal funding available for the bureau's 85 percent share and the Casitas district would be obligated ob·li·gate tr.v. ob·li·gat·ed, ob·li·gat·ing, ob·li·gates 1. To bind, compel, or constrain by a social, legal, or moral tie. See Synonyms at force. 2. To cause to be grateful or indebted; oblige. to pay the remaining 15 percent. Dealing with environmental issues Residents downstream of the dam and other community groups have been pushing for the project to begin on time. They mostly are satisfied the bureau will deal with significant environmental issues such as dust, vegetation and wildlife during the project - even notifying residents and motorists to guard against Valley Fever valley fever: see coccidioidomycosis. spores that might be released by excavating. ``We raised a lot of issues. We're usually the ones that are asking for the extended environmental review,'' said Russ Baggerly, president of Citizens to Preserve the Ojai and a board member for the Environmental Coalition of Ventura County. ``But the historical data is real clear,'' he said. ``That data necessitates that this dam gets fixed pretty damn fast.'' Residents also said the bureau seems to be responding to their primary concern that an emergency warning system be installed before construction begins. In July, the bureau joined officials for the water district, county Sheriff's and Fire Departments and the National Weather Service to begin planning such a system. Pennington said it would be activated in an emergency, such as an earthquake or flood, and may include radio broadcasts and sirens. He said an emergency evacuation For other uses, see Evacuation. Emergency evacuation is the movement of persons from a dangerous place due to the threat or occurrence of a disastrous event. Examples are the evacuation of a building due to a bomb threat or fire and the evacuation of a district because of a plan for residents downstream also must be in place. The fear of flooding in the wake of a natural disaster is significant for leaders of the Westside Community Council, which represents businesses and residents in the area that would be inundated in·un·date tr.v. in·un·dat·ed, in·un·dat·ing, in·un·dates 1. To cover with water, especially floodwaters. 2. . The council said in a recent letter to the bureau: ``As concerned citizens, we are requesting that you install such a system prior to beginning this work, as such a disaster would affect thousands of lives in our community.'' ``This is serious,'' Baggerly contended. ``Nothing's ever been there. We want to have a permanent early-warning system.'' CAPTION(S): Map MAP: Ventura County Dionisio Munoz/Daily News |
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