Idaho’s surface water users and groundwater pumpers are close to finalizing a new mitigation plan to secure the water supply for senior water right holders and avoid curtailment for junior water users.

“The major terms of the agreement have been reached in principle, and there’s some finer details being worked out,” said Thomas J. Budge, attorney for the Idaho Ground Water Users Association.

But it’s not a done deal until the board of directors of the various groups involved approve it, he said.

Meetings between water users this summer, mediated by Lt. Gov. Scott Bedke, followed a curtailment order for junior water users issued in May in which water users came to only a temporary agreement.

Stabilize aquifer

The new proposed plan is designed to stabilize the aquifer and provide a mechanism that more effectively meets the irrigation needs of the seniors with storage water and other projects that will improve their water supply, he said.

“One thing we discovered this year was that curtailment is an extremely inefficient way to provide water to the seniors when they need it. And the objective of the pumpers has been to develop a management system that is more effective at getting water to the seniors when they need it without drying up vast amounts of farmland,” he said.

The curtailment order would have shut off about 1.6 million acre-feet of water use to get 75,000 acre-feet out of the springs this irrigation season,” he said.

Ineffective management

An “unbelievable” amount of farmland would have to be dried up to get a comparatively small amount of water out of the springs, he said.

“It’s not good for anybody to manage the resource that way. So our objective from the groundwater side is to come up with a better management strategy that does not use curtailment as the way to mitigate water supply shortfalls to the seniors,” he said.

This new plan would provide more storage water to the seniors when they need it and not provide water when they don’t, he said.

Under the old settlement agreement, the juniors had to deliver 50,000 acre-feet of storage water to the seniors every year whether they needed it or not. Under the new agreement, the juniors would deliver the amount actually needed up to 75,000 acre-feet.

Groundwater conservation

The new plan will require pumpers to continue conserving water to stabilize the aquifer, and it allows some flexibility in doing that. It allows averaging of conservation over four-year periods, and that was important to the juniors, he said.

It also would create a larger pool of storage water that juniors can use to mitigate injury to the seniors and allows juniors to develop other projects that will improve senior water supplies, such as conversion and recharge.

“I’m pleased with the outcome. I think it’s mutually beneficial to both sides. It’s a better strategy for managing the resource. It continues the success we’ve had at conserving water and stabilizing the aquifer, and it provides a more cost-effective way to mitigate water supply shortages to the seniors,” he said.

The draft agreement would be a mitigation plan for 12 years.

“Our hope is to have it finalized by the end of October, ” he said.

• The director of the state Department of Water Resources issued the curtailment order on May 30 to meet a projected water supply shortage of 74,100 acre-feet to senior water right holder Twin Falls Canal Co.

• It originally impacted about 64,000 junior water rights in six groundwater districts that were not operating under an approved mitigation plan. It threatened about 500,000 acres in eastern and south-central Idaho.

• Two groundwater districts got on board with a mitigation plan in early June, and the remaining four worked out a temporary compromise with senior water right holders for 2024 in mid-June.