Water Intelligence Brief — Twin Falls County, ID

October 5, 2026 | Agricultural Water Edition

Situation Summary

Snake River flows at Milner Dam are reading 0 cfs as of October 5, consistent with end-of-season diversion operations, while the downstream Twin Falls gauge shows 512 cfs — reflecting return flows and spring contributions below the diversion point. For irrigators, this signals that the main irrigation season is effectively closing at Milner, with late-season field operations and harvest logistics now driving any remaining water demand. Reservoir storage data and 7-day forecast details are available in the full brief.

Snowpack Conditions

All three SNOTEL stations in the Twin Falls County monitoring network are reporting 0.0" snow water equivalent (SWE) and 0.0" snow depth as of October 4 — the single exception being Wilson Creek, which shows a trace reading of 0.3" SWE with 0.0" measured depth.

For this point in the calendar, 0.0" SWE at Lewis Lake Divide, Magic Mountain, and Wilson Creek reflects normal seasonal conditions — median SWE for early October at these elevations is also 0.0", so no below-normal signal is present in today's snapshot. The relevant 2026 snowpack story is one of timing: across the upper Snake River basin, snowpack melted out approximately 4–6 weeks ahead of the historical median meltout date, a consequence of the anomalous March heat event. That early meltout shaped the summer supply trajectory — it is background context now, not the current operational signal.

New snowpack accumulation at Lewis Lake Divide and the Teton-area headwaters through October and November will begin establishing the early signal for the 2027 irrigation season.

Streamflow Conditions

Snake River at Milner Dam (13087995): 0 cfs, stable, as of October 5. This is the defining gauge for Magic Valley water delivery — it records what is available at the point where Twin Falls Canal Company (south bank) and Northside Canal Company (north bank) together divert into the approximately 202,000-acre irrigation system. A reading of 0 cfs at Milner at this date reflects end-of-season diversion conditions, consistent with late-season operational drawdown.

Snake River near Twin Falls (13090500): 512 cfs, stable, as of October 5. This gauge sits downstream of the Milner diversion and captures a drainage area of approximately 22,360 square miles of upper basin contribution. The 512 cfs reading here, against 0 cfs at Milner, reflects the reappearance of flow below the diversion — primarily from Eastern Snake Plain Aquifer spring discharge and return flows entering the canyon reach between Milner and Twin Falls. This is a characteristic late-season pattern for the Magic Valley reach of the Snake River.

Seasonal Guidance

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

Data Sources: SNOTEL data through October 4, 2026; USGS streamflow data through October 5, 2026.

Data Current As Of: October 5, 2026. SNOTEL data via NRCS National Water and Climate Center; streamflow data via USGS National Water Information System.

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), Twin Falls Canal Company (primary south-bank diverter at Milner Dam), Northside Canal Company (primary north-bank diverter at Milner Dam), 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.