Idaho curtails groundwater rights junior to October 11, 1900, the largest call of the sequence
On May 14, 2026 the IDWR Director ordered curtailment of ESPA groundwater rights junior to October 11, 1900, against a predicted in-season shortfall of 181,600 acre feet. Roughly 930 rights lacked mitigation coverage; the July mid-summer order left the date unchanged.
- Curtailment date
- Junior to Oct 11, 1900
- Predicted shortfall
- 181,600 AF
- Rights not covered by a plan
- ~930
- Heise June-July forecast
- ~50% of normal
What happened
The Director of the Idaho Department of Water Resources issued a final order on May 14, 2026 curtailing groundwater rights junior to October 11, 1900 within the ESPA Area of Common Ground Water Supply, in response to the Surface Water Coalition delivery call. The April methodology order had predicted an in-season shortfall of 181,600 acre feet, versus 74,100 in 2024 and 63,000 in April 2025.
Roughly 930 rights were identified as not covered by an approved mitigation plan. The July 22 mid-summer methodology order found a continued shortfall and left the curtailment date unchanged; IDWR reported it had addressed 87 percent of the affected rights with another 11 percent under investigation. The June joint forecast put unregulated flow at the Heise gage for June and July at 900,000 acre feet, about half of normal.
What it means if you own water here
An 1899 right and a 1901 right on the same ground had completely different seasons. This is prior appropriation doing exactly what it is designed to do, and it is the clearest demonstration in the West of why priority datePriority dateThe date a water right was established, which sets its place in line during shortage. The earlier the date, the more reliable, and more valuable, the right. is the first number in any valuation.
For junior holders, the lesson is the mitigation plan. Compliant groundwater districts and their patrons had safe harbor; uncovered rights did not. Idaho’s water bank, with statutory protection against ForfeitureForfeiture (use it or lose it)The doctrine by which a water right unused for the statutory period, commonly five consecutive years, can be lost in whole or part. Approved leases and bank deposits protect against it., is the standing alternative for water you are not using.
Article Sources
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