RENO, Nev. (AP) - The chief government engineer overseeing an irrigation canal that broke and flooded nearly 600 homes in northern Nevada in January sought to reassure a federal judge on Wednesday that current reduced flows in the canal are safe.
But David Gore, regional engineer for the U.S. Bureau of Reclamation's Mid-Pacific region based in Sacramento, also acknowledged the construction standards used when the earthen canal was built in 1903 were significantly less stringent than those required today.
And the judge who is considering a request by more than 100 flood victims to further restrict the flows continued to raise concerns that deficiencies blamed for the canal's failure still might exist, including the presence of rodent burrows suspected of weakening the embankment.
Gore told U.S. District Judge Lloyd George that the Truckee Carson Irrigation District operating the Truckee Canal for the bureau has met all the agency's safety measures and required repairs necessary to allow the current canal flows of 350 cubic feet per second.
Water was flowing at the canal's capacity of 750 cfs when the embankment burst at 4 a.m. on Jan. 5, flooding 590 homes in Fernley. It marked at least the ninth time the canal has failed since it was built, although past events caused little damage because housing developments have been built along the canal only in the past decade in the previously rural community 30 miles east of Reno.
Hundreds of flood victims have filed a lawsuit against the bureau, TCID and others, and are seeking a restraining order to restrict flows to 250 cfs - a level TCID says would deprive about 2,000 farmers and ranchers of much of the water they need for their crops and livestock.
Testifying in the third day of a hearing that's been continued over several weeks, Gore said that extensive review of the entire 31-mile canal makes him confident the risk of another failure at 350 cfs is far below the industry standard of one in 100.
"The canal has never failed to our knowledge ... when operated below flows of 400 cfs," he said, although he admitted the actual flows were not known for as many as three of the previous failures.
Robert Hager and other lawyers for flood victims point to a report the bureau's 12-member risk assessment team issued in March that warned any flows greater than 150 cfs would result in a "high" risk of another failure. That team also cited concerns about the erodible nature of the soils used to construct the embankment, with a poor compaction rate of 70 percent to 84 percent compared to today's required standard of 95 percent.
"The compaction in the embankment is consistent with what was being done when it was constructed in the early 1900s," Gore said Wednesday. "It does not meet the current design standards for a new canal."
Gore said his confidence in the integrity of the canal is buoyed by the fact TCID was required to adopt a rodent control program and fill all known rodent holes - most of them dug by muskrats - before flows were raised above 150 cfs in May.
But Judge George pointed to photographs lawyers for the flood victims presented showing some burrows still exist.
Gore said the bureau directed TCID to "go out in the field and fill them all."
The judge asked, "Are you telling me you filled all the rodent holes?"
Gore replied: "That's not to say the rodents aren't still out there. So there's likely some holes out there."
Dave Overvold, TCID's project manager for the canal, said he was confident they had filled all the holes that existed but acknowledged some "could reappear." He said the district has contracted with a private company, Critter Control, that has set traps for rodents and already has caught seven muskrats.
The Truckee Canal and Carson River are the primary sources of water for the Lahontan Reservoir, which Overvold said currently is storing about 120,000 acre feet of water but is projected to be down to only 4,000 acre feet by the end of August.
"It will be virtually empty," he said, cutting short an irrigation season that typically stretches into October or November.
Even at 350 cfs, water users in the Truckee Division are going to receive only about 90 percent of their normal supply and users in the Carson Division will receive only about 75 percent of their normal supply, Overvold said.
After about seven hours of testimony, Judge George closed the hearing and told the lawyers they would be allowed to make closing
arguments at a future undetermined time via teleconference before
he rules on the motion for a preliminary injunction to restrict water flows.
(Copyright 2008 by The Associated Press. All Rights Reserved.)