Idaho water officials try to avoid Swan Falls curtailment scenario

If Snake River flows drop below a minimum level at the Murphy streamgage, 2,500 upstream water rights could be subject to curtailment. State water officials will work with those water right holders to develop a plan to try to preclude that from happening.

BOISE — Idaho water officials will work with water right holders to formulate a plan to avoid the mass curtailment scenario that could develop if Snake River stream flows near Murphy fall below a certain level.

Under the 30-year-old Swan Falls Agreement, the state has guaranteed Idaho Power that flows at the Murphy stream gage will not fall below a minimum of 3,900 cubic feet per second in the summer or 5,600 cubic feet per second in the winter.

If flows fall below those minimum levels, about 2,500 water rights could be curtailed.

Stream flows at the Murphy gage south of Boise have come close to those minimum levels in recent years, said Jeff Peppersack, chief of the Idaho Department of Water Resources’ water allocation bureau.

The IDWR has initiated a contested case against those water rights, which include more than 1,400 irrigation rights. The goal of the administrative move is to bring the parties together to develop a plan to avoid curtailment, Peppersack said.

The case could simply mean that the parties get together and try to form some type of solution outside of the actual formal process, he said.

“That’s definitely the better option — to find a way to allow (these) water right holders to continue to divert water and still not threaten the minimum stream flows,” he said. “That’s hopefully where we’re going to end up.”

Under the 1984 Swan Falls Agreement, the state agreed to increase the minimum stream flows at Murphy so that Idaho Power would have sufficient water for power generation.

This avoided the possible curtailment of 7,500 water rights upstream from Idaho Power’s Swan Falls facility and what state officials said would have been catastrophic consequences for agriculture in Southern Idaho.

The agreement also paved the way for the development of an additional 107,000 acres of irrigated land as well as supplemental water rights for an another 72,000 irrigated acres, said Clive Strong, chief of the Idaho Attorney General Office’s natural resources division.

Those ground and surface water rights that were developed after Oct. 25, 1984, were placed in a trust administered by the state. They are subordinate to existing uses at the time of the agreement and can be curtailed if stream flows fall below those minimum levels.

Some of those rights have a 20-year term condition and will be reviewed by the IDWR to determine whether they remain in the public’s best interest.

The state has formed a working group that includes affected water right holders with the goal of developing a monitoring and management plan that seeks to avoid a possible curtailment scenario, Strong said.

“We’re going to bring them into the process now and try to get them engaged so that they understand what their exposure is and ... help define the solution so there is no need for curtailment,” he said.

http://www.capitalpress.com/Idaho/20...lment-scenario


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