Damned Dams

Dams have been supplying water and controlling floods for hundreds of years. But what happens with they fail?

In 1889, the Johnstown dam in Pennsylvania broke, killing over 2,200 people. Above is an illustration of the break and a picture of the devastation. Currently, roughly 5% (or 4,400) of dams in the US are considered safety hazards.  Fixing these dams would cost billions of dollars, money that we don't have. Therefore, in order to deal with these comprised dams, officials have reduced holding levels and developed evacuation plans.. After the Gulf oil spill, I'm not convinced these interim measures are enough. A huge unexpected storm (the result of climate change, of course) could open the floodgates.

From an environmental standpoint, the construction of dams was a horrible idea. They disturb essential habitat and block paths for fish like salmon, which swim up river to reproduce. They disrupt natural erosion and sedimentation cycles, destroy wetlands, and alter temperature regimes.

However, dams made place for cities to flourish, and if they were to break, thousands of lives would be at risk. Also, the billions of gallons of water released from a break would not only carry an enormous amount of debris and sediment but also accumulated lead, mercury,  PCBs, nitrogen, and (guess what.) invasive species. The environmental consequences could be devastating to areas downstream, and a return to the ecosystems of old may be impossible. However, it has been shown that dam removal can help restore wetlands, temperatures, and salmon pathways.

So, do we remove the dams? Do we wait for something to happen? Or, do we fix them?