Aging dams threaten cities, store less water
Rehabilitating all high-hazard dams could cost $16 billion
By MATEUSZ PERKOWSKI
Fixing dams in the U.S. is like running on a treadmill that's rapidly gaining speed.
Although rehabilitation projects are ongoing, they're not keeping up with the pace of deterioration, according to dam experts.
"Over the past six years, for every deficient, high-hazard dam repaired, nearly two more were declared deficient," according to a report by the American Society of Civil Engineers.
The upkeep of dams earned a "D" grade in the society's report card on U.S. infrastructure.
State dam safety officials estimate the total cost of rehabilitating high-hazard dams at about $16 billion, with the backlog having increased by about 60 percent since 2003.
In many cases, populations around dams have swelled as the structures have aged, heightening the risk. Roughly two of three dams are more than 40 years old.
Many structures were built in uninhabited areas where potential failures wouldn't have endangered people or their property, said Brian Pallasch, managing director of government relations for the ASCE. Those surrounding areas have since changed.
"As cities have grown, folks have begun living closer and closer to dams," Pallasch said.
Since 2000, the U.S. has averaged more than five dam failures a year, resulting in tens of millions of dollars in damage to homes, businesses, bridges and highways, according to the Association of State Dam Safety Officials.
Dam deterioration can have an impact on irrigators and other water users even when the structure stays intact.
When funds aren't available for major repairs, regulators try to mitigate the risk of a major catastrophe by reducing the amount of water in the dam's reservoir, said David Gutierrez, the association's former president and chief of the dam safety division at California's Department of Water Resources.
The association has found that 4,400 dams in the U.S. are susceptible to failure from structural or hydraulic deficiencies.
More than 70 percent of those structures are considered to pose a high or significant hazard, meaning their failure would probably cause death, environmental damage or economic disruption.
"The potential hazards in the far West are obviously earthquakes," Gutierrez said. "That's where a lot of the resources are being spent right now."
Preparing older dams to withstand an earthquake involves more than simple repairs. Occasionally, the structures have to be replaced altogether.
Rehabilitation may require thickening the dam with a concrete downstream berm or strengthening its foundation to prevent liquefaction -- a phenomenon in which shaken and saturated soils basically turn to liquid, Gutierrez said.
"We didn't know that when these dams were built in the '40s, '50s and '60s, but we know that now," he said.
California, where the prospect of earthquakes looms large, has the one of the most robust dam safety programs in the U.S.
With about $10.5 million in its dam safety budget -- more than any other state except Florida -- California has one dam safety employee for every 21 dams. Nine high-hazard and significant-hazard dams in the state are in need of rehabilitation.
Oregon has eight such dams in need of repair, with one regulatory employee per 370 dams. At $122,000, the state's dam safety budget is the third smallest in the country.
In Washington, which has a regulatory budget of $1.1 million and one employee per 69 dams, there are 35 high-hazard and significant-hazard dams in need of rehabilitation.
Idaho has one dam safety employee for 134 dams and a regulatory budget of about $312,000. The state has seven high-hazard and significant-hazard dams that require fixing.
Dam safety oversight appears light in some of the states that seem to need it most.
Oklahoma, for example, has 150 high-hazard dams that need repair -- the third-highest number in the U.S. -- but only one regulatory employee per 1,600 dams.
Alabama has more than 2,200 dams but zero funding for dam safety regulation.
"Some states don't have the resources to enforce the authority," Gutierrez said. "A lot of the country is in trouble."
The upside of water scarcity in states like California is that infrastructure projects are more economically feasible, he said. Because water is expensive, dam owners earn more from water users and are better able to afford repairs.
About 90 percent of the nation's 84,000 dams are owned by private parties, local governments and public utilities.
The best solution to the repair backlog would be to provide these entities with a financial incentive for rehabilitation, such as installing income-generating hydroelectric and irrigation facilities, Pallasch said.
"This is not only a federal government problem," he said.
Even so, Congress could start the process by creating a matching funds program for dam repairs, or establishing an "infrastructure bank" that would lend money to private investors for major construction and rehab projects, Pallasch said.
Such an approach would also boost the economy, he said. "From the stimulus standpoint, this is a way to create jobs."