OJAI : Matilija Dam Repair Options Discussed

Matilija Dam, built to control flooding and provide water for the Ojai Valley, is filling up with silt, officials say.

“Something has to be done with it in the near future,” said County Flood Control Director Gerald Nowak. “The next major rainfall will probably silt it up.”

The dam, set in rugged Matilija Canyon five miles north of Ojai, was declared safe for the people who live below it after the annual inspection by the Division of Dam Safety, said John Johnson, general manager of Casitas Municipal Water District.

However, he said, “Should the crest have to be lowered again, effectiveness of Matilija Dam would disappear.”

If the dam fails, floodwaters would hit the communities of Ojala in five minutes, Meiners Oaks in 10 minutes, Oak View in 35 minutes and Casitas Springs in one hour, according to the county Dam Failure Response Plan.

If sediment were removed from Matilija Lake behind the dam, it would better protect the area from floods and would yield Casitas Municipal Water District up to 2,000 annual acre-feet of water, even if the drought continues, said Richard Barnett, the district’s chief engineer.

One acre-foot of water supplies a family of four for one year.

Left as it is, the lake’s yield would drop to 200 acre-feet after the year 2010, Barnett said.

Fragile since it was built in 1948, the dam holds only 14% of its original capacity because it was built of unstable concrete that expands and splits, weakening the structure.

By 1965, state dam safety officials had ordered the dam’s crest lowered twice. This reduced strain on the dam by cutting the lake capacity in half, from 7,000 to 3,350 acre-feet of water.

Winter rains have settled 4.4 million cubic yards of sediment behind the dam, leaving room for only 1,100 acre-feet of water, Barnett said.

Officials want to finance a study to determine whether the dam could withstand a higher volume of water or if it could be rebuilt as a safer, earthen-fill dam to reach its former capacity.

Nowak, of the flood control agency, expected to split the $100,000 cost of a study of the dam with the Casitas Municipal Water District this year. But the Board of Supervisors cut the county’s share from the budget.

Flood control and Casitas engineers regularly monitor the dam.

“It really gets looked after,” said James Logsdon, resident dam tender who keeps an eye on it for Casitas, operates the valves and chases off trespassers.

Matilija Lake was a popular swimming and fishing hole until a flood in 1969 wiped out a campground and boating concession.

Since then, stricter drinking water regulations and higher insurance costs have forced the water company to keep people away.

Sgt. Don Cunningham of the Sheriff’s Department’s Ojai substation estimates that deputies have issued 400 misdemeanor citations in the past year to trespassers who are fined $200 to $300.