Jerome County, ID — Agricultural Water Intelligence Brief

September 21, 2026 | Free-Tier Edition

Situation Summary

Late-season Snake River deliveries via Northside Canal Company are entering the final weeks of the 2026 irrigation season, with alfalfa fifth and sixth cutting windows and dairy operation water demand defining this week's operational priorities. Jerome County's 80%-storage-dependent supply profile means current delivery reliability traces directly to how American Falls and Palisades reservoirs entered this season — reservoir carryover, not today's streamflow, is the number that matters most for Jerome County dairy and alfalfa producers. Reservoir storage data and 7-day forecast details are available in the full brief.

Snowpack Conditions

Lewis Lake Divide (SNOTEL Station, 7,880 ft — Teton County, WY):

As of September 20, 2026, Snow Water Equivalent (SWE) reads 0.0 inches with snow depth of 0.0 inches. No percent-of-median is shown for this date, which indicates the historical median SWE for late September at this elevation is also 0.0 inches — this is the normal seasonal condition for this point in the calendar, not a below-normal reading.

Lewis Lake Divide is the far-upstream snowpack indicator most relevant to Jerome County: Continental Divide snowpack at this station governs inflow to the upper Snake River, Jackson Lake, Palisades Reservoir, American Falls Reservoir, and ultimately Milner Dam diversions. For a county that is 80% storage-dependent, this station's winter and spring accumulation was the early predictor of the 2026 season's supply months before the first irrigation call. As background context, the 2026 season was shaped by an anomalous March heat wave that drove meltout at Lewis Lake Divide and across the upper Snake River headwaters approximately 4–6 weeks ahead of the historical median meltout date — accelerating reservoir inflows earlier in the spring than storage operators could fully capture.

No additional SNOTEL stations were provided in the data for this brief period.

Streamflow Conditions

No active USGS streamflow gauges within Jerome County boundaries are available for this brief. Jerome County has no in-county agricultural supply gauges — the county's closest stream monitoring point is a small spring vent with a negligible drainage area, not a supply indicator.

Jerome County's definitive streamflow references are the Snake River at Milner (USGS 13087995, pre-diversion supply indicator above the dam) and the Snake River near Twin Falls (USGS 13090500, basin integrator below Milner). Neither gauge is physically within Jerome County, but both are the standard operational references for Northside Canal Company delivery management on the north bank. No USGS gauge data was provided in the current data context for either station.

During active irrigation season, near-zero Snake River flow below Milner Dam is normal canal operations — the Milner Diversion Dam captures essentially the full river for Northside and Twin Falls Canal Company diversions. This is not a crisis signal. Supply anomalies for Jerome County irrigators are read from above-Milner flow levels and, more importantly, from upstream reservoir storage status — not from below-dam readings.

Contact Northside Canal Company directly for current delivery status and canal operational schedules.

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 Idaho Department of Water Resources (IDWR — administers Water District 36, the middle Snake River priority system), Northside Canal Company (primary north-bank diverter at Milner Dam, serving approximately 85,000 acres across Jerome, Lincoln, and adjacent counties), A&B Irrigation District (USBR Bureau of Reclamation project serving northern Magic Valley area in Jerome and Lincoln counties), and U.S. Bureau of Reclamation, Pacific Northwest Region (Boise office — for American Falls and Palisades upstream reservoir storage context). American Falls Reservoir and Palisades Reservoir are not available in the USBR RISE API for Idaho facilities (verified June 2026) — contact USBR Pacific Northwest Region or IDWR Water District 36 directly for current storage data before making irrigation or carryover planning decisions.