U.S. Energy Information Administration - EIA - Independent Statistics and Analysis
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The Northwest River Forecast Center's latest forecasts for 2012 show near- or below-normal water supply for April to September (the typical high hydro season). The map above shows observation stations in the watershed region of the Pacific Northwest with forecasts for the percent of normal water supply for that station. The colors of the stations represent forecasted water supply levels above normal (blue), near normal (green and yellow), or below normal (orange and red).
Significant quantities of water flowing in the Northwest are used to generate electricity. As such, water supply forecasts are particularly important for operators of electric generators in this region.
The overall water supply is broadly made up of the precipitation that falls in a given time period, the snowpack held throughout a watershed, and the subsequent runoff of the melting snow in the watershed. Each of these phases in the water cycle has observed data tracked by the Northwest River Forecast Center (NWRFC).
Forecasts of runoff volumes at dams with hydroelectric generators are of particular interest to operators of hydroelectric generators. The water volumes for the Dalles Dam, a centrally located run-of-river dam on the Columbia River, is forecasted to be below the 30-year average for April through September.
Note: 2006-2011 are actual volumes. For 2012, the NWRFC forecast as of 2/15/2012 predicts a 90% chance runoff will meet or exceed the level shown above.
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Hydroelectric supply has significant price effects as well as implications for the dispatch of other generators (such as wind turbines and thermal generators) in the Pacific Northwest. In contrast to a relatively low output from hydropower this coming summer, hydroelectric output in 2011 was significantly above normal levels well into the summer, an unusual occurrence that drove down wholesale electricity prices in much of the western United States.