A negotiated management plan that has helped resolve a long-standing conflict between groundwater and surface water users in the Wood River Basin has been extended for three more years, a topic discussed in detail during the Idaho Water Users Association annual convention in January.
Unlike a settlement or mitigation plan, this effort takes a more holistic approach, addressing multiple angles to find a lasting resolution. Guided by the Idaho Department of Water Resources (IDWR), the Wood River Valley Ground Water Management Area Plan has evolved significantly from the early settlement concepts first discussed.
“I think the extended plan is very innovative,” said Shelley Keen, deputy director for IDWR, during the convention.
The conflict at the heart of the management plan stems from groundwater pumping by junior water rights holders in the Wood River Valley, Bellevue Triangle and arguably the Camas Prairie, reducing surface water availability for senior rights holders – some with rights dating back to the 1880s – in areas south of the Wood River Valley.
Establishing the Big Wood River Groundwater Management Area in 1991 was an early step in managing groundwater impacts on surface water rights in Basin 37. However, Keen noted that the path to the first three-year version of the management plan in 2021 has not been smooth, with multiple delivery call attempts by surface water users against groundwater users, procedural setbacks and a 2021 curtailment of groundwater that highlighted the need for an alternative, structured approach.
Pat Purdy, a Wood River Valley farmer and representative of the South Valley Groundwater District, shared his perspective as both a groundwater and surface water user. “We had 30 years to figure this out, and the director finally put his foot down and gave us three days to figure it out,” he said, referring to the 2021 curtailment. “We were off for a little more than a week. Interestingly enough, 36 hours after the pumps were off, we saw a response in Silver Creek – a significant response. It was pretty hard to argue that there wasn’t a connection between our pumping and what was going on in Silver Creek.”
“I would just encourage you all if you are involved in a situation like this, don’t let it get to this point because this isn’t a fun place to be,” Purdy said.
Cooper Brossy, representing the Big and Little Wood Water Users Association, explained that the original management plan for 2022-24 was tested under varying conditions – 2022 being a challenging water year, and while 2023 was more favorable, 2024 came with its own surprises and a chance to learn about the plan. By early 2024, stakeholders saw the need for revisions. In response, IDWR Director Mathew Weaver urged them to create a long-term plan designed to remain effective for 10 to 15 years.
“This kind of upped the ante,” Brossy said. “Everyone took it pretty seriously and said, ‘Well, this plan better work really well for all.’”
Now extended through 2027, the renewed Big Wood River Groundwater Management Plan builds on the 2021 framework with improved management actions to promote sustainable groundwater use while protecting senior water rights under the prior appropriation doctrine. While additional analyses and discussions are ongoing to prepare for a long-term plan, key elements of the current plan include the following.
Seasonal predictability and scaled use reductions
A key goal of the plan is to provide season predictability of available surface and groundwater supplies, allowing all users to develop practical plans for the year ahead. This predictability and planning rely on a synthesis of several water supply forecasts and agreed-to supply thresholds that trigger scaled reductions in groundwater withdrawals and other management actions.
“As a groundwater user, I want to know before I put seed in the ground whether I’m going to be able to raise a crop or not,” Purdy said, highlighting the importance of this provision. “We really struggled with figuring out a way to do this – what the timing looked like – and we settled on around the first of April each year. By then, we need to have pretty decent predictability because that’s when we start planting in our basin.”
Building on this need for clear expectations, the renewed management plan prioritizes scaling groundwater use to match annual water supply forecasts, ensuring long-term sustainability for both groundwater and surface water users. “We want to provide access to groundwater resources, but those have to be scaled to each year's water supply forecast,” Brossy said. “We can't be overdrawing the bank account every year, year after year.”
Fallowing
The original plan required fallowing as an annual conservation measure but lacked provisions for adjusting or suspending it during wet years. The renewed plan still requires the two groundwater districts in the basin to fallow, but only when forecast water supplies are below a set threshold.
“This is a difficult one – it’s difficult to track and difficult to incentivize. But the senior surface users felt like this was a very important element in the plan,” Purdy said, emphasizing its value in dry years. Producers facing drought must decide whether to fallow some ground or risk spreading their water too thin and yielding little in return.
Brossy acknowledged the difficulty in incentivizing producers to fallow ground. However, it is a way to cut down the consumptive use in a tough but, certainly, a clear and demonstrable way, he said. If more widespread real-time monitoring of aquifer withdrawals were implemented, the blunt tool of strict fallowing could probably be reduced, Brossy commented.
Shorten the season of use
To further conserve water, the plan shortened the irrigation season. Groundwater pumping now begins on May 1 instead of April 15 and ends on Sept. 15 instead of Sept. 30. The front-end reduction is manageable since most users have access to surface water early in the season. However, the early cutoff in the fall poses challenges for producers planting fall crops, organic certifications or cattle grazing. “So we do have some exceptions built in,” Purdy emphasized.
The main goal with the earlier shutoff is to allow the aquifer to recharge before winter, Brossy said. Without this recovery period, the aquifer could be sufficiently depleted that it will soak up most of the spring runoff, preventing water from reaching Magic Reservoir and flowing downstream to users below.
Stream flows
The management plan sets a target flow rate on the Little Wood River near Richfield, ensuring a baseline supply of surface water for senior users. If the flow target is not met, groundwater users must take additional steps to support stream flow, such as self-curtailment or other measures. The key, Purdy said, is that this provides a single metric everyone can monitor in real time and adjust accordingly.
Storage water
The management plan requires groundwater users to supply Snake River storage water to senior surface water right holders when stream flows decline. Speaking on the importance of storage water to the plan, Brossy said, “It allows juniors to continue pumping and withdrawing from the aquifer while keeping senior folks wet. We’re willing to go without on the senior side as long as junior users are willing to turn their pumps off. But if they have a crop they need to finish, they can bring in some storage water, and everyone gets along.”
Safe harbor
A critical component for groundwater users is the "safe harbor" provision, which protects them from curtailment as long as they actively participate in and comply with the plan.
Financial support plan
Brossy said another important element that helped “seal the deal” for some people was incorporating financial support. Municipal entities and HOA-type groups contribute to the Conservation Infrastructure and Efficiency Fund, paying per acre-foot of groundwater withdrawn. This fund supports improvements to the water supply system for delivering senior water, protecting groundwater, increasing surface water flows and improving measurement management. A portion also funds cloud seeding operations and future infrastructure development, he said.
“We were able to arrive at this point because we negotiated in good faith,” Purdy said of the experience. “We’ve had plenty of disagreements, but we’ve been able to work through those and the department has been huge in helping with that and guiding us in this process. … we didn’t get everything we wanted, but we got some of what we wanted.”
As Keen noted, the region’s water users must remain engaged in refining and implementing the plan, particularly as new scientific data becomes available. With climate variability and increasing demands on water resources, ongoing collaboration will be essential to ensuring a reliable water future for the Wood River Basin.
For now, the renewed agreement stands as a testament to the power of negotiation in resolving water conflicts. While Idaho’s broader water battles continue to unfold, the Wood River Valley has demonstrated that compromise and innovation can lead to solutions that benefit all water users.
