Upper Snake reservoir system Oct. 31 volume avoids ’03 low

The Upper Snake River reservoir system ended the water year with its second lowest level in 30 years. Irrigation shutoffs and above-average precipitation during October kept month-end volume from falling beneath the 30-season low, which occurred in 2003, according to figures from Idaho Falls, Idaho-based state Water District 1 The high came in 2017. Oct. 31 volume is a benchmark for system carryover into the following year because irrigation winds down during the month. The low 2026 total reflects that carryover at the end of the 2025 irrigation season was below average, and “then, we had very poor snowpack over the winter,” WD 1 watermaster Craig Chandler said. As for the 2026 irrigation season, “the year had low storage allocations and high storage demand,” he said At present, the April 1 forecast of Snake River stream volume as measured at the Heise gauge northeast of Idaho Falls needs to exceed 120% of normal to have a chance of filling the system, Chandler said.

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