Aging dams threatened by climate change

Record heavy rains in the Pacific Northwest last winter unleashed floods and landslides and overtopped some of the region's giant concrete dams. Heavy winter snows in California's Sierra Nevada Mountains and in the central Rockies left Western officials fearing warm spring weather, rapid snowmelt, and more floods.Such worries are increasing across the West as climate change creates greater fluctuations in watershed flows that infrastructure was not built to withstand. Add the fact that dams and levees are aging and ill-maintained because federal and state budget cupboards are bare, and wherever you look, there's the possibility for a perfect storm of flooding and costly infrastructure failure. Take for example, Northern California's privately owned Sacramento Delta levee system. It gets little oversight. A 2004 levee failure, cause unknown, flooded 12,000 acres of farmland for six months. Future levee collapses, prompted by flood, drought, earthquake, or age and poor upkeep, could allow saltwater intrusion into the Delta, the drinking water source for two-thirds of Californians. Ultimately, taxpayers bear the costs of rebuilding after such "natural disasters." Solutions won't be easy or cheap. During the twentieth century, water managers planned for future needs based on past precipitation patterns. But with climate change, weather patterns are more unpredictable, and we haven't yet determined how to adapt. In several western states, for example, water managers have traditionally relied on the melting mountain snowpack throughout spring and summer to supply water during dry months. Those snowpacks once provided nearly three-quarters of the West's water. No more. Earlier, warmer springs are melting snowpacks more quickly, leaving less for late summer. Rapid snowmelt is also putting increased pressure on aging infrastructure, including dams not designed to withstand it and overflowing reservoirs too small to accommodate it.There are 87,000 dams in the U.S., according to the Association of State Dam Safety Officials (ASDSO). The vast majority are privately owned, and many no longer serve their planned function. About 10 percent have no known owner. ASDSO found that 10,127 dams nationwide pose a serious threat to human life if they fail, and of those, 1,333 were structurally deficient or unsafe. Even worse, many cities have developed their floodplains, putting new businesses and homes in the path of future floods and dam or levee breaks. Increased flooding is predicted in 10 out of 12 U.S. cities evaluated in a recent climate change study by the Natural Resources Defense Council (NRDC). We can also expect saltwater floods. Sea level rise could flood parts of San Francisco, Seattle, Los Angeles, Boston, Miami, New Orleans, New York City, and Norfolk, Va. says NRDC. Saltwater intrusion into drinking water supplies threatens Los Angeles, San Francisco, Miami, and New York. Floods and sea level rise also jeopardize critical, low-lying infrastructure: airports, bridges, highways, pipelines, railroads, refineries, ports, water treatment plants, and nuclear plants, as seen during this summer's Missouri River flood at Fort Calhoun, Nebraska. Western cities need to adapt now. All new infrastructure plans should pass muster not only under past climate conditions but also those modeled for the next fifty years. These plans should meet a resiliency bar. For example, why plunk down $1.5 billion turning San Francisco Bay's Treasure Island into a "green" development when it's barely three feet above sea level? Instead, we need to spend limited funds shoring up critical infrastructure that we can't do without or can't move and embrace new types of infrastructure designed for "soft failure" by bending rather than breaking. I'm talking about innovations like low-impact development - porous pavements and rain gardens that absorb rainwater into the earth, decreasing flooding. We also need regulations that discourage construction in floodplains and along vulnerable coasts by pushing developers to shoulder the financial risk of disaster. Building codes must be updated too, reducing flood risk. Dams that have outlived their function should be removed. The evidence of changing water patterns is all around us. We have a choice: adapt now, and prepare for the floods to come, or pay a high price in property damage and human suffering later. Freelance reporter Erica Gies has been published by The New York Times, The International Herald Tribune, Wired News, Grist, and E/The Environmental Magazine. To comment on this column go to www.blueridgepress.com ©BRP 2011

********** Published: November 17, 2011 - Volume 10 - Issue 31