Cassia County Water Intelligence Brief

September 7, 2026 | Free-Tier Edition

Situation Summary

Late-season streamflow conditions across Cassia County are running low and declining, with the Raft River near Malta recording just 2 cfs on a falling trend — a signal of tightening supply for Raft River Valley ranchers entering the final weeks of the irrigation season. Snake River corridor irrigators in the Burley/Rupert area are navigating end-of-season canal delivery conditions under a snowpack that melted out 4–6 weeks ahead of schedule, compressing the effective supply window for the year. Reservoir storage data and upstream American Falls and Palisades operational details are available in the full brief.

Snowpack Conditions

All three SNOTEL stations serving Cassia County are reporting zero snow water equivalent and zero snow depth as of September 6 — a normal condition for this calendar date, as median SWE at these elevations is also 0.0" in early September. No below-normal language is warranted based on current readings.

The relevant 2026 snowpack story is timing: stations across the region melted out 4–6 weeks ahead of the historical median meltout date, driven by an anomalous March heat wave. That early meltout accelerated spring runoff, reduced late-season storage accumulation in upstream reservoirs, and shortened the effective surface water delivery window — effects that are now embedded in current streamflow and storage conditions.

Streamflow Conditions

Two distinct streamflow zones define Cassia County's water supply picture this week.

Snake River Corridor: No active USGS Snake River gauge exists within Cassia County boundaries — supply assessment for the Burley Irrigation District service area relies on upstream and downstream reference points outside the county. Cassia Creek below Blacksmith Creek is reading 4 cfs and holding stable as of September 7, providing a localized tributary signal for the northern county. This modest flow is consistent with late-season conditions on small in-county drainages.

Raft River Valley: The Raft River above Onemile Creek near Malta (USGS 13078000) is recording 2 cfs on a falling trend as of September 7. At 2 cfs and declining, available surface water for Raft River Valley ranchers and irrigators is minimal. This gauge is the primary in-county streamflow indicator for southern Cassia County's ranching and hay operations — the falling trajectory warrants close attention as alfalfa and hay operations approach the close of the irrigation season.

Seasonal Guidance

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

Data Sources: SNOTEL data through September 6, 2026; USGS streamflow data through September 7, 2026. Stations: Bostetter R.S., Howell Canyon, Lewis Lake Divide (NRCS SNOTEL); Cassia Creek below Blacksmith Creek (USGS); Raft River above Onemile Creek near Malta, ID — USGS 13078000 (USGS NWIS).

Data Current As Of: September 7, 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; Burley district office is the point of contact for Cassia County water rights administration), Burley Irrigation District (primary delivery infrastructure for the Snake River corridor), and U.S. Bureau of Reclamation, Pacific Northwest Region (Boise office), for regulatory decisions and water rights administration.