Water Intelligence Brief — Twin Falls County, ID

June 15, 2026 | Free-Tier Edition

Situation Summary

The 2026 irrigation season across the Magic Valley opened under an early-melt signature: SNOTEL stations monitoring the upper Snake River basin melted out 4–6 weeks ahead of the historical median meltout date, meaning the seasonal snowpack pulse arrived earlier than normal rather than arriving now. Snake River flows at the critical Milner diversion point are currently reading zero, signaling that the Twin Falls Canal Company and Northside Canal Company diversion system requires close attention as mid-June demand peaks. Reservoir storage data for American Falls and Palisades — the upstream storage facilities governing late-season supply to Magic Valley — and 7-day forecast details are available in the full brief.

Snowpack Conditions

All three SNOTEL stations monitoring the upper Snake River basin headwaters are reporting 0.0 inches SWE and 0.0 inches snow depth as of June 14, 2026:

No percent-of-median figures are shown for any station — this is expected, as the historical median SWE for these stations at this point in mid-June is also 0.0". The stations are at their normal seasonal condition for this calendar date. The meaningful signal for 2026 is meltout timing, not current SWE: all stations melted out 4–6 weeks ahead of the historical median meltout date, driven by an anomalous March heat wave across the Mountain West. That early meltout means the snowmelt runoff pulse — which normally extends into late June — has already moved through the upper basin. Galena Summit's early clearance is particularly relevant for Twin Falls County irrigators, as Big Wood River tributary inflows to the Snake River near the Gooding/Twin Falls county boundary reflect Sawtooth Range snowmelt conditions monitored at that station.

Streamflow Conditions

Two USGS gauges bracket the core Magic Valley diversion zone:

The Milner gauge reading is the most operationally critical data point for Magic Valley irrigators. At 0 cfs, the gauge indicates that the Twin Falls Canal Company (south bank) and Northside Canal Company (north bank) are diverting essentially the full Snake River flow at Milner Diversion Dam into the approximately 202,000-acre Magic Valley canal system — a normal condition during peak irrigation season, when the river below Milner characteristically runs at near-zero. This is not a failure condition; it reflects the design of the Milner diversion system. However, it does mean that any reduction in upstream inflow translates directly and immediately into reduced canal delivery capacity, with no buffer at the diversion point itself.

The Twin Falls gauge at 403 cfs reflects return flows, spring contributions, and local drainage entering the Snake River downstream of Milner — not a meaningful upstream supply indicator. The upstream supply chain — what is arriving from Wyoming, Yellowstone, and eastern Idaho mountain ranges across the 22,360 square mile drainage area above this gauge — is governed by American Falls and Palisades reservoir operations, which are not captured in this free-tier brief.

Seasonal Guidance

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Data Sources: SNOTEL data through June 14, 2026; USGS streamflow data through June 15, 2026

Data Current As Of: June 15, 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), 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 storage context) for regulatory decisions and water rights administration.