Cassia County Water Intelligence Brief

September 21, 2026 | Free-Tier Edition

Situation Summary

Late-season streamflow in Cassia County's two agricultural zones is minimal but stable: Raft River above Onemile Creek near Malta reads 6 cfs (rising) and Cassia Creek below Blacksmith Creek reads 4 cfs (rising), reflecting normal end-of-irrigation-season conditions across the county's surface water systems. For Snake River corridor irrigators in the Burley/Rupert area, the critical supply variables now are upstream American Falls and Palisades Reservoir storage levels and Burley Irrigation District delivery status as potato and sugar beet harvest demand enters its final weeks. Reservoir storage data and 7-day forecast details are available in the full brief.

Snowpack Conditions

All three SNOTEL stations reporting for Cassia County show no measurable snow water equivalent or snow depth as of September 20:

No percent-of-median figures are shown for any station, meaning the median SWE for this calendar date is also 0.0" — these stations are at their normal seasonal condition for late September, not below normal. The relevant 2026 snowpack story is timing: across the region, stations melted out 4–6 weeks ahead of the historical median meltout date following an anomalous March heat event. That early meltout is background context for the season's supply trajectory, not the current operational condition.

Streamflow Conditions

Two USGS gauges provide the primary in-county surface water signal for Cassia County's two distinct agricultural zones.

Raft River Valley (south county): The Raft River above Onemile Creek near Malta (13078000) reads 6 cfs and rising as of September 21. For Oakley-area ranchers and hay irrigators, this is a modest but functional late-season flow. The Raft River system operates at low volumes in late summer — the 6 cfs reading is within the range expected for this point in the season. The rising trend is a modestly positive signal worth monitoring.

Cassia Creek (south county indicator): Cassia Creek below Blacksmith Creek reads 4 cfs and rising as of September 21, consistent with late-season base flow conditions in the smaller tributary drainages of southern Cassia County.

Snake River Corridor (north county): No active USGS Snake River gauge exists within Cassia County boundaries. Supply assessment for the Burley Irrigation District service area relies on upstream reference points outside the county. Irrigators and processing industry water managers should contact Burley Irrigation District directly for current delivery status.

Seasonal Guidance

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

Data Sources: SNOTEL data through September 20, 2026; USGS streamflow data through September 21, 2026.

Data Current As Of: September 21, 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 at (208) 678-1280), 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 and for regulatory decisions and water rights administration.