Dam reservoirs emit more harmful gases than believed

Thursday, September 29, 2016by  Jon Osterberg

Researchers at Washington State University have learned that hydroelectric reservoirs, common in the Northwest, produce more harmful greenhouse gases than previously believed.
     The culprit is underwater organic material and runoff fertilizer that decomposes, releasing gases such as methane that radiate heat into the atmosphere.
     WSU’s researchers found that reservoirs emit about 25% more methane than previously known, according to a Sept. 28 Seattle Times article.
     The Northwest is home to many hydroelectric dams and reservoirs. The Columbia River basin alone accounts for 44% of the nation’s hydropower, according to the U.S. Energy Information Administration. Four of the nation’s seven largest hydropower stations are here – Grand Coulee, Chief Joseph, John Day, and The Dalles dams.
     Five of our country’s 25 largest reservoirs are found in or near the Northwest. Roosevelt Lake, impounded behind Grand Coulee, is the nation’s 6th largest. Others are Montana’s Fort Peck (No. 5), Koocanusa (No. 9), and Hungry Horse (No. 22), and Idaho’s Dworshak (No. 21). Shasta Lake, south of the Oregon border, ranks No. 14.
     Other large local reservoirs include Banks Lake, Lake Umatilla, Lake Wallula, Riffe Lake, Ross Lake, Brownlee Reservoir, and Owyhee Reservoir.
     Though the discovery of higher greenhouse-gas emissions changes our perception of hydroelectric reservoirs being carbon neutral, hydropower remains far less harmful than other fuels. The United States Geological Survey notes several advantages to hydropower:

  • No fuel burned, so minimal pollution
  • Water provided free by nature
  • Relatively low operations and maintenance costs
  • Reliable, proven technology
  • Rainfall is renewable.

     Yes, we still can count on rain in the Northwest.

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