Cassia County Water Intelligence Brief

September 14, 2026 | Free-Tier Edition

Situation Summary

Late-season streamflow in both of Cassia County's agricultural zones is running at low volumes typical for mid-September, with Cassia Creek falling at 3 cfs and the Raft River near Malta holding at 3 cfs and rising — conditions that signal the irrigation season is in its final stretch for Snake River corridor operators and that Raft River Valley ranchers should monitor any uptick closely. Snowpack stations are fully melted out, as expected for this calendar date, and the operational story now centers on delivery reliability through harvest and the adequacy of upstream storage to sustain Burley Irrigation District diversions into October. 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 conditions consistent with normal mid-September status:

Zero SWE at this point in the calendar is the expected seasonal condition — the median SWE for mid-September at these elevations is also 0.0", so these readings do not indicate below-normal snowpack today. The relevant 2026 snowpack story is one of timing: across the region, stations melted out 4–6 weeks ahead of the historical median meltout date, driven by an anomalous March heat wave. That early meltout compressed the spring runoff pulse and reduced the recharge window for upstream reservoirs and the Eastern Snake Plain Aquifer earlier in the season. Howell Canyon's data gap should be noted — users relying on that station for early-season monitoring in 2027 should confirm instrument status with NRCS before the accumulation season begins.

Streamflow Conditions

Cassia Creek below Blacksmith Creek (09/14): 3 cfs, falling trend. This tributary flow in the Snake River corridor portion of the county reflects typical late-season recession. The falling direction is consistent with declining irrigation return flows and diminishing baseflow contribution as the season winds down.

Raft River above Onemile Creek near Malta (13078000) (09/14): 3 cfs, rising trend. For Raft River Valley ranchers and irrigators in the Oakley and Malta area, the rising signal at 3 cfs is a modest but noteworthy departure from the typical late-season falling pattern. At this flow level, the Raft River remains a limited supply source — sufficient for stock water and small diversions but not a high-volume irrigation resource. Ranchers should verify whether the rising trend reflects localized precipitation or upstream conditions before adjusting operations.

Snake River corridor note: No active USGS Snake River gauge exists within Cassia County boundaries. Supply assessment for the Burley Irrigation District service area relies on upstream gauges at Milner and near Twin Falls. Users assessing Snake River delivery conditions should contact the Burley Irrigation District or IDWR Water District 36 (Burley office) directly for current diversion status.

Seasonal Guidance

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Data Sources: SNOTEL data through September 13, 2026; USGS streamflow data through September 14, 2026.

Data Current As Of: September 14, 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, primary point of contact for Cassia County water right administration and call status), 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 storage context. Raft River Valley users should contact IDWR Eastern Regional Office in Pocatello, (208) 525-7161, for surface water administration on the Raft River system. This brief does not constitute legal, engineering, or water rights advice.