WAPA delivers power mostly from hydroelectric dams in the region.
Agency spokesman Randy Wilkerson says WAPA will increase rates by nearly 23 percent on Jan. 1.
He attributes the increase to several years of drought, which resulted in reduced power production from Missouri River dams and forced WAPA to buy more expensive power elsewhere. While the drought has eased, moisture in the region has not been excessive.
"Even though we seem to have had a little bit of recovery this past year, those reservoirs aren't full yet," Wilkerson said. "And when the reservoirs aren't full, that reduces the generation, so we've got less electricity to provide, and when that happens we've got to go out on the open market and purchase that power to make up what we've contracted with."
WAPA has raised rates by nearly 18 percent in the past two years.
"Our rates, by legislation, are cost-based, and so ultimately the consumers end up paying for that down the road," Wilkerson said.
WAPA has begun a regional environmental impact study on wind power, he said. The agency hopes wind-generated electricity can provide a portion of its power in the future, Wilkerson said.
"When hydropower is short, maybe it could be supplemented with wind," he said.