Northeast’s Aging Dams Threatened By Climate Change

By Erica Gies

In August Hurricane Irene brought dramatic flooding to Vermont, dumping 11 inches of rain in 24 hours. Floodwaters washed away roads, homes, bridges, businesses, and the state’s emergency operations center, leaving a dozen mountain towns cut off from the outside world. The costly deluge did major harm from North Carolina to New England, making it the tenth weather disaster of 2011 to cost more than $1 billion. That’s a record.

Unfortunately, floods are becoming more common across the Northeast because climate change is creating greater fluctuations in watershed flows that U.S. infrastructure was not built to withstand.

Add the fact that dams 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.

In Massachusetts, for example, emergency workers were forced to tear down the 200-year-old Forge Pond Dam in Freetown when rainstorms last year pushed the structure to its limit. If the dam had failed, two others downstream probably would have failed as well, said a public safety official.

Ultimately, taxpayers bear the costs of rebuilding after such “natural disasters.” But 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 learned to adapt.

The now-regular occurrence of “100-year” and “500-year” floods is putting increased pressure on dams not designed to withstand it. There are 87,000 dams in the United States, says 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 eastern cities and towns have developed their floodplains, putting new businesses and homes in the path of future floods or dam breaks. Increased flooding is predicted in 10 out of 12 U.S. cities evaluated in a climate change study by the Natural Resources Defense Council (NRDC).

We can also expect saltwater floods. Sea level rise could flood parts of New York City; Boston; Norfolk, Va.; San Francisco; Seattle; Los Angeles; Miami; and New Orleans, says NRDC. Saltwater intrusion into drinking water supplies threatens New York, Los Angeles, San Francisco, and Miami.

Floods, sea level rise, and storm surges also jeopardize critical, low-lying infrastructure: airports (such as New York’s JFK International), bridges, highways, pipelines, railroads, refineries, ports, water treatment plants, and even nuclear plants (such as the Salem, N.J., plant just south of Philadelphia).

Eastern cities need to adapt now – and many are. For example, in Montpelier, Vt., which suffered back-to-back “100-year” floods this year, officials have increased the capacity of city culverts.

All new infrastructure plans must pass muster not only under past climate conditions, but also those modeled fifty years from now. These plans should meet bars for resiliency and common sense – and are beginning to. For example, during the 20th century, federal agencies dreamed of engineering an expensive tunnel system to ease natural flooding on New Jersey’s Passaic River. Now state and federal governments are instead buying out area properties prone to flooding.

We should 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, decreasing flooding.

We also need regulations that discourage construction in floodplains and along vulnerable coasts (like New Jersey’s Barrier Islands), by pushing developers to shoulder the financial risk of disaster. Building codes must be updated, 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 ©BRP 2011

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