Idaho Surface and Ground Water Users Reach Agreement (For Now). What It Means:
After months of closed-door conversations between Idaho’s Surface Water Coalition (SWC), Eastern Snake River Plain Aquifer (ESPA) groundwater district representatives, the Idaho Department of Water Resources, and the state’s own Lt. governor- a new water mitigation plan has been finalized.
The beginning of the 2024 irrigation year in Idaho began with confusion and panic as senior surface water right holders called for a 74,100-acre feet of water shortfall to be delivered by the junior groundwater districts according to the state’s Prior Appropriations Doctrine. It was suddenly very uncertain whether 500,000 acres in those junior groundwater districts would go unirrigated to meet this obligation, and national media groups were quick to broadcast this dilemma across the world.
Ultimately the impasse was averted when the State’s Governor (Brad Little) and Lt. Governor (Scott Bedke) intervened and encouraged an emergency, short term agreement to get through this year’s irrigation season. However, an ultimatum was also given requiring a long-term, clear-cut mitigation plan had to be hashed out before the end of October.
As legal agreements go, the resulting mitigation plan appears to be clear and straightforward. Whether it is an agreement that both sides of the waterline can work with in perpetuity remains to be seen. Here is a short list of key points in the new agreement:
This agreement sets forth four year “compliance periods” starting 2024-2027 where allocations, storage requirements, and recharge efforts are grouped.
‒ All groundwater districts in this agreement will be allocated a volume of water that can be diverted during that 4-year compliance period as outlined by the chart below.
‒ “Each district may divert more or less than one-fourth of their compliance period allocation in any given year so long as the total amount diverted during a compliance period does not exceed the districts total (4-year) allocation.”
‒ Surplus water from 2024-2027 compliance period will be carried over to the next 2028-2031 compliance period. “Reach gain” measurements will be reviewed in the 2031 annual meeting to determine if any remaining surplus will continue to carry into subsequent compliance periods.
“Reach gains” are the volumes of water that Eastern Snake River Plains Aquifer (ESPA) contributes to the Snake River. Use of groundwater in the ESPA common groundwater area has been shown to diminish reach gain levels and subsequent availability to downstream senior surface water right users. Thus, their measurement is an important part of the implementation of this plan.
Aquifer recharge efforts made by districts may supplement their compliance period allocations. Recharge is not mandatory in this plan. Districts are granted supplemental allocations if and when they choose to do recharge efforts. Greater detail as to what type and where this recharge may occur is outlined in the agreement.
Measurement and reporting of non-irrigation diversion in the ESPA groundwater management area will now happen on an annual basis.
Irrigation diversion, who have long been required to measure their diversion, are now required to have functioning programs by the beginning of 2026 to read and record these irrigation diversions monthly. This measurement data will be made publicly available.
The Idaho Water Resource Board will contribute $5,000,000 for projects aimed at maximizing/increasing reach gains through the Blackfoot to Minidoka area. Beginning 2035 the districts will collectively have to deposit $250,000 to a bank account annually to fund continual development and implementation of improvement projects.
‒ If reach gain levels drop below the 2023 levels, districts will then be required to deposit $500,000 annually until 4-year average reach gains equal or exceed 2023 levels.
Ground water districts must secure a combined total of 75,000 acre-feet of supplemental storage water for the 2025 and 2026 seasons to be delivered to the Surface Water Coalition.
‒ If the reach gains (again, reach gains are the amount of water the aquifer contributes to the Snake River measured at inlet streams annually) in 2026 are greater than 2023, then districts will continue to secure and deliver the combined total of 75,000 AF supplemental storage water in 2027.
‒ If reach gains are lower, districts are required to secure and deliver up to (but not exceeding) 82,500 combined total AF. It is not clear whether a shortfall in 2026 will have to be made up on a one-to-one basis, only that that the reach gain will be greater than the initial 75,000 AF but not more than 82,500 AF.
‒ At the annual meeting in 2027, discussions will be held and an amendment made determining storage water requirements moving forward.
An oversight committee will be created to review the implementation of this plan with chair members from both surface water and groundwater groups.
Each district will be independently responsible for their compliance. If one district does not comply, it will not adversely affect any other district.
More provisions, greater details to the provisions stated here, can be found in the full document of the 2024 Stipulated Mitigation Plan.
What does this agreement mean for Idaho groundwater irrigation moving forward? While we cannot predict the future anymore than if the rain will fall, here are some thoughts as to what farming of Idaho’s Eastern Snake River Plain might look like moving forward:
Increased curtailment of groundwater patron allocations may be likely. Districts will watch annual precipitation and snow-pack carefully as above average water years will be important in their efforts to meet storage requirements and for recharge efforts.
Groundwater districts have received greater autonomy in their mitigation management and recharge plans with this agreement. This was a major concern and contributor to the confusion coming into the 2024 season.
The cost of groundwater seems likely to go up beginning in 2035 as the districts will collectively be required to deposit at least $250,000 into a bank account annually. These funds will likely be raised via district water fees.
The agreement demonstrates the importance of the Blackfoot to Minidoka reach gains and how the IDWR measures, monitors, and models the hydrological movement of water throughout the ESPA.
The inclusion of additional groundwater districts is planned for in this agreement and implies that more acreage could be included in the ESPA common groundwater management area.
And finally,
Water will continue to be the main driver of productivity and opportunity for agriculture in the Western United States. As such producers, manager, and land owners alike must continue to carefully monitor these policy changes and be actively engaged in their personal water districts.