The Role of Hydroelectric Power in the United States
ENERGY IN BRIEF ARTICLE
November 29, 2011
The importance of hydropower as a source of electricity generation varies by geographic region. While hydropower accounted for 6% of total U.S. electricity generation in 2010, it provided over half of the electricity in the Pacific Northwest. Because hydroelectric generation relies on precipitation, it varies widely from month to month and year to year.
Conventional hydroelectric generators of varying capacity operated in 48 states in 2010. Operating expenses for hydroelectric generators are lower than for most other forms of electricity generation but facilities are limited by geography and operations are subject to seasonal constraints. There is a large concentration of capacity in the Pacific Northwest, contributing to low wholesale and retail electricity prices in that region, especially in the spring runoff season.
Read the entire article: http://www.eia.gov/energy_in_brief/hydropower.cfm