BOISE - The state may be in danger of violating the Swan Falls Agreement because a drought is drying up the Snake River, according to a statement released late Tuesday by the Idaho Department of Water Resources.

The complicated agreement,–established by the Idaho Legislature in 1984,–guaranteed Idaho Power Co. 3,900 cubic feet per second for use in its Swan Falls hydropower facilities near Murphy.

But the agreement has ramifications for nearly every water user on the Eastern Snake River Plain. At stake is control over much of southern Idaho's water.

Earlier this year, the utility filed suit in 5th District Court against the state in a move to rework the agreement. If the power company loses, it claims it will likely have to raise rates for its customers. If the state loses, it means less state authority to appropriate and control water.

"The Swan Falls issue is a fundamental issue for Idaho water," said IDWR Director Dave Tuthill.

Earlier this week, the department sent letters to 83 surface-water users who divert water from the Snake River or its tributaries. The letters warned the users they may have to stop diverting if flows dip below 3,900 cfs at Murphy.

Idaho Power did not return calls for this story, but in May, Greg Panter, vice president of public affairs at the utility, said a showdown between Idaho Power and the state would be likely if flows dipped below 3,900 cfs this summer.

"The state of Idaho won't be receiving calls from Clear Springs," said Panter, referring to requests from trout producer Clear Springs for the state to ensure water owed to them. "It'll be coming from Idaho Power."

Panter blames the state for not effectively managing southern Idaho's intricate water network that includes the Eastern Snake Plain Aquifer, an underground sponge-like water system about the size of Lake Erie, and the Snake River.

The state says the minimum flows are in danger because of drought.

The utility wants those minimum flows guaranteed, but it's also claiming ownership to water above those flows to generate more low-cost electricity. The state says anything above 3,900 cfs should go into a trust managed by the state. The state had earmarked that water for recharge - a process of returning water to the aquifer to boost spring flows in the Thousand Springs reach.

"We're like anybody else at the table," Panter said in the May interview. "We want ours. There's no question about that."

Swan Falls will likely be a topic at an IDWR hearing on Oct. 10 between groundwater pumpers and trout producers Clear Springs Foods and Blue Lakes Trout Farm regarding recent state plans to curtail the pumpers' wells. Those plans were called off Thursday, and some believe the Swan Falls Agreement nullifies the trout farms' ability to take water from junior groundwater pumpers with less-senior rights.

Times-News staff writer Matt Christensen covers the environment. He welcomes comments at 735-3243 and at matt.christensen@lee.net.