By NICHOLAS K. GERANIOS

Associated Press

SPOKANE, Wash. (AP) -- Proposals to take water from behind Grand Coulee Dam to expand one of the nation's largest federal irrigation projects will be released this week by the U.S. Bureau of Reclamation.

The agency's draft environmental impact statement addresses how to get more Columbia River water to many more farmers. One option calls for drawing 10 times more water from the river, enough to irrigate more than 100,000 acres.

The 640,000-acre Columbia Basin Project takes more than 3 million acre-feet of water each year from the reservoir behind the dam. An acre-foot is the amount of water needed to cover an acre to a depth of one foot, or about 325,850 gallons.

Some environmental groups oppose the expansion, contending that the diversions harm salmon migration and water quality, and that they are an expensive and unneeded subsidy for farmers.

"This proposal comes at a time of growing public concerns about wasteful government spending and public deficits," said the Center for Environmental Law and Policy in Spokane, which has long opposed the project. Taxpayers would be on the hook for new canals and dams, and the huge costs of pumping water over the Grand Coulee Dam to the new farm areas, it added.

The draft will be released Tuesday at the Columbia Basin Development League's annual meeting. That group is a major proponent of expanding agribusiness on the Columbia Plateau.

"This is an extensive study on supplying surface water to lands being irrigated by groundwater," said Jim Blanchard of the Reclamation Bureau office in Ephrata.

The long-awaited draft, which was originally to be released this summer, does not identify which plan the agency prefers, he said. And any actual expansion depends on funding from Congress, he said.

The Columbia Basin Project was started during the Great Depression of the 1930s, but was never completed to its planned 1 million acres. Farmers who started working land in areas that were not irrigated used wells to pump groundwater from the Odessa Aquifer.

That water supply, which serves some 379 rights holders, has been declining at the rate of about 7 feet per year.

The water converted the arid lands west of Spokane, Wash., into farms, many producing potatoes that are turned into french fries.

Copyright 2010 The Associated Press.