Cassia County Water Intelligence Brief

July 20, 2026 | Free-Tier Edition

Situation Summary

Cassia County enters the critical late-season irrigation window under a post-meltout supply regime, with all monitored snowpack stations reporting zero snow water equivalent — consistent with normal mid-July seasonal conditions following an extremely early 2026 meltout across the Mountain West. The Snake River corridor (Burley/Rupert area) is now fully dependent on upstream American Falls and Palisades reservoir carryover and Eastern Snake Plain Aquifer groundwater, while the Raft River Valley is operating on minimal in-stream flows. Reservoir storage data, 7-day forecast details, and depletion trajectory analysis are available in the full brief.

Snowpack Conditions

All three SNOTEL stations reporting for Cassia County and the surrounding supply watersheds have reached their normal seasonal meltout condition as of July 19, 2026:

Zero SWE at all three stations is the expected condition for mid-July — the median SWE for this date is also 0.0", so these readings do not indicate below-normal snowpack *today*. The operationally significant finding for 2026 is timing: stations across the region melted out approximately 4–6 weeks ahead of the historical median meltout date, driven by the anomalous March heat wave. This early meltout compressed the spring runoff pulse and reduced the window for American Falls and Palisades reservoir filling upstream on the Snake River. No new snowmelt contribution to streamflow or aquifer recharge is available from these stations for the remainder of the irrigation season. The Snake River corridor is fully reliant on stored water and groundwater for the duration of the 2026 season.

Streamflow Conditions

Two USGS gauges provide in-county surface water data for Cassia County's two distinct agricultural zones:

Cassia Creek below Blacksmith Creek, ID: 6 cfs, stable as of July 20. This gauge reflects conditions in the smaller tributary system of the Snake River corridor — a modest but stable reading consistent with base-flow conditions at this point in the season.

Raft River above Onemile Creek near Malta, ID (13078000): 2 cfs, rising as of July 20. This gauge is the primary streamflow indicator for the Raft River Valley agricultural zone in southern Cassia County. At 2 cfs, in-stream supply is minimal — consistent with the ranching and limited-irrigation character of the Oakley/Malta area, where the Raft River supports small-scale hay and alfalfa irrigation and livestock watering rather than high-intensity irrigated production. The rising trend is a modest positive signal and warrants monitoring.

Important note for the Snake River corridor: No active USGS Snake River gauge exists within Cassia County boundaries — the Snake River near Burley gauge (13085045) is discontinued. Supply assessment for the Burley Irrigation District service area relies on upstream gauges outside county boundaries. Irrigators and Amalgamated Sugar's Burley factory operations should monitor Burley Irrigation District delivery status directly for current canal supply conditions.

Seasonal Guidance

Subscribe for the full brief including reservoir storage, weather forecasts, depletion analysis, and detailed operational recommendations.

Data Sources: SNOTEL data through July 19, 2026; USGS streamflow data through July 20, 2026.

Data Current As Of: July 20, 2026.

Important Disclaimers: This brief provides automated analysis for informational purposes only. Specific numerical claims have not been independently verified. Consult official sources including your local water district, Idaho Department of Water Resources (IDWR — administers Water District 36, the middle Snake River priority system; Burley district office), Burley Irrigation District (primary delivery infrastructure for the Snake River corridor in Cassia County), and U.S. Bureau of Reclamation, Pacific Northwest Region (Boise office — for American Falls Reservoir and Palisades Reservoir upstream context) for regulatory decisions and water rights administration.