BISMARCK, N.D. -- High water levels that caused record flooding along the Missouri River in 2011 did bring a small consolation: Electric power generation from the river's six upstream dams was above average for the first time in a dozen years.
The U.S. Army Corps of Engineers, which manages dams and reservoirs along the 2,341-mile river, said energy production from the dams in the Dakotas, Montana and Nebraska totaled 11.1 billion kilowatts of electricity last year and was the highest since 1999. And for the first time in more than a decade, the U.S. Energy Department's Western Area Power Administration got ample electricity from the dams and did not have to buy power on the open market to fulfill contracts.
Mike Swenson, a corps engineer in Omaha, Neb., said the increased hydropower is of little salve to the scores of people affected by the 2011 flood along the river, which flows from Montana through North Dakota, South Dakota, Nebraska, Kansas, Iowa and Missouri.
"It's hard to put to a silver lining on a year like we had last year, but it is good to have generation back up," Swenson said.
The water storage level of the six upstream reservoirs in the Missouri River system is nearly 57 million acre-feet at present, equal to last year and at the ideal level, Swenson said. An acre-foot is the amount of water covering one acre, a foot deep.
The corps said the plants have generated an average of 9.3 billion kilowatt-hours of electricity since 1967, including a high of 14.6 billion kilowatts in 1997.
The plants generated 8.7 billion kilowatt-hours in 2010, up from 6.6 billion kilowatt-hours in 2009. During the driest years in the past decade, power plant output fell below 5 billion kilowatt-hours in 2007 and 2008, the corps said.
After about a decade of drought, the six reservoirs in the Dakotas, Montana and Nebraska began rebounding in 2008 with more mountain snowmelt and wetter weather.
Previous years of parched conditions shrunk the reservoirs' storage level to 33.9 million acre-feet in February 2007, an all-time low, the corps said.
Dry conditions also cut electric power generation, forcing the Western Area Power Administration to spend more than $1.5 billion since 2000 buying power from other, more expensive sources to fulfill contracts, the agency said.
Lisa Meiman, a WAPA spokeswoman in Lakewood, Colo., said 2011 was the first year in a decade that the agency did not have to buy supplemental power.
Meiman said the Missouri River reservoirs are WAPA's largest producer of energy. The administration buys and sells power from 56 hydropower plants around the nation.
Swenson, the corps engineer, said the six upstream reservoirs had record releases last year due to heavy rains in western states and melting snow.
Oahe Dam near Pierre, S.D., which holds Lake Oahe in the Dakotas, and Garrison Dam, which creates Lake Sakakawea in western North Dakota, are typically the biggest power producers in the Missouri River system, Swenson said.
Not all of the high water was used by hydroelectric turbines, Swenson said. Excess flows were funneled through emergency outlet tunnels, bypassing powerhouses, he said. At Garrison Dam, the corps opened the spillway gates for the first time in the dam's half-century history to help draw down swollen reservoir levels.
Oahe Dam generated 3.3 billion kilowatt-hours last year, up from 2.5 billion kilowatt-hours in 2010 and just below the long-term average of 2.6 billion kilowatt-hours, Swenson said. The dam recorded a low of 1.1 billion kilowatt-hours in 2007.
Garrison Dam generated 2.6 billion kilowatt-hours of electricity last year, up from 2.1 billion in 2010 and a low of 1.3 billion in 2008, Swenson said. The long-term average at the dam is 2.2 billion kilowatt-hours.