Fighting over water is a popular sport in the West, where generations of lawyers have refined the practice until it approaches an art. Often, the quantities at stake are prodigious, the output of entire watersheds. In other instances, however, the volume is so minuscule as to leave outsiders puzzled by all the fuss.

A dispute of the latter sort is threatening to break out in Ventura County, where an unusually broad coalition of interests has united behind one of the largest dam-removal projects in American history. As federal, state and local agencies press forward with environmental review and demolition planning, a handful of opposing voices have strained to make themselves heard. Having failed so far to secure the guarantees they desire, they have begun offering thinly veiled threats of legal action to stop the project or at least delay it — a move that could prove fatal to critical funding.

The dispute is an illustration that, in California, there is no such thing as a trivial amount of water, and that even the most marginal dams have their defenders.

Matilija Dam, completed in 1948 in a rugged canyon 16 miles north of Ventura, was envisioned as a means of providing flood control to a handful of small downstream communities and recharging groundwater supplies used by farmers in the sparsely populated Ojai Valley. With so few potential beneficiaries, the dam had such a dismal cost-benefit ratio that no state or federal agency could be persuaded to build it. Undaunted, the dam’s backers persuaded local voters to pass a bond measure to provide funding, and the county flood control district tackled the task.

Problems were apparent nearly from the start. Cracks began appearing on the downstream face of the dam almost immediately after completion, and they worsened over time. A 1959 survey revealed that the dam’s crest was tilting upstream, probably because a chemical reaction between alkali in the cement and silica in the aggregate used in the concrete was causing it to expand and deteriorate. Concerned about the dam’s safety, the county twice had the dam’s crest notched to lower it and reduce stress on the foundation. The dam originally was 198 feet tall; subsequent modifications lowered it 30 feet.

Bad concrete was not Matilija Dam’s only flaw. The mountains surrounding it are rising rapidly and eroding nearly as rapidly, producing huge amounts of debris. Matilija’s 7,000-acre-foot reservoir first filled with water in 1952. But it also had begun filling with sediment — about 79 acre-feet a year, according to a 1954 report by the U.S. Bureau of Reclamation (BOR). By 1969, the reservoir’s storage capacity had been cut in half.

According to the BOR, the dam now traps 6 million cubic yards of sediment, the equivalent of 14 Rose Bowl stadiums full of sand, silt, gravel and cobbles. The reservoir has a storage capacity of about 500 acre-feet and provides no flood control, although it does provide a trickle of water to supplement the supply of the Ojai area’s main water provider, the Casitas Municipal Water District (CMWD).

The dam contributes to beach erosion by trapping sand that would otherwise reach the coast, and blocks access to critical spawning grounds for endangered southern steelhead in the Ventura River watershed. Efforts to demolish the dam and restore the ecosystem have been under way since 1998, when local advocates secured federal support for a feasibility study.

Strategies for taking out the dam and dealing with the sediment behind it are detailed in a technical analysis released in June and are examined further in a draft EIR/EIS released in July, opening a pubic-comment period that closed August 30. Almost simultaneously, local lawmakers announced that $79 million in federal funding for the $110 million project had survived committee scrutiny in Congress and made it into this year’s federal Water Resources Development Act.

The Army Corps of Engineers is the lead agency under the National Environmental Policy Act (NEPA). The Ventura County Watershed Protection Agency (former the county flood control district) is the lead agency under the California Environmental Quality Act (CEQA). A final record of decision on the project is expected by the end of the year.

Dealing with the trapped sediment is the most costly aspect of the project. There is too much to haul away, and allowing it to be eroded naturally by storm flows after the dam is gone would cause the lower river to be buried beneath debris, smothering habitat and increasing the flood risk. Under the preferred alternative, the fine silt would be dredged out, transported downstream in a slurry line and piled up outside the main river channel. The remaining coarse sediments would be stabilized temporarily in the old reservoir site in such a way that extremely high flows would erode them gradually and carry them downstream.

Legislative support reflects the extremely broad coalition of interests united in support of the removal project, including virtually every federal, state and local agency with an interest in the dam or in steelhead, as well as a lengthy roster of environmental groups.

At a July 28 public hearing on the draft EIR/EIS, however, representatives of CMWD and some small rural water agencies complained that the document fails to address the effect of the dam removal on their water supply. And at least one of those representatives argued that this failure left the document open to challenge under CEQA and NEPA — a hint of litigation to come.

He may have a point: The EIR/EIS acknowledges a potential temporary reduction in supply as a consequence of the project., but vaguely waves off the impact by noting that replacement water could be purchased from the State Water Project or “obtained from other sources” — the kind of “paper water” assurances California judges increasingly seem disinclined to tolerate.

In a state where individual farms consume thousands of acre-feet a year, the amount of water at stake seems trivial. The Casitas district has a lease with the dam’s owner, the Ventura County Watershed Protection District, to store water behind the dam. That water is dribbled through the dam’s outlet works into the river channel after winter’s peak flows have subsided, allowing it to be diverted downstream by CMWD.

According to the BOR, Matilija Dam adds an average of 590 acre-feet a year to the local water supply. Casitas provides conflicting estimates. In a July 20 letter to the editor of the local newspaper, the agency’s board president asserted that Matilija reservoir provides “about 600 acre-feet of water.” A July 21 press release from the district asserts that removal of the dam could cause the district’s customers to lose 2,400 acre-feet. In a more recent press release, the district claims Matilija yields 790 acre-feet of water a year, a figure repeated in a recent interview with Casitas General Manager John Johnson.

Regardless of which figure is correct, Mother nature has ideas of her own. Continuing sediment deposition, the EIR/EIS warns, will reduce Matilija Reservoir’s capacity to 150 acre-feet by 2010 and less than 50 acre-feet by 2020.

Even before sedimentation eliminates the reservoir, the water district will lose access to it. The district’s lease with the dam’s owner expires on Jan. 1, 2009 — about the same time the dam would start to come down, if the project moves forward. And it is unlikely the county will be interested in renewing that lease, as it is spearheading the removal process.

John Johnson, Casitas Municipal Water District, (805) 649-2251.
Jeff Pratt, Ventura County Watershed Protection District, (805) 654-2001.
Draft dam removal EIR/EIS: