Caribou County, ID — Water Intelligence Brief

September 21, 2026 | Free-Tier Edition

Situation Summary

Bear River flows are active and mixed in direction across the basin this week, with the mainstem at Pescadero falling while downstream readings near Corinne are rising — a pattern that reflects shifting reservoir operations and tributary inputs rather than a uniform supply signal. With the primary irrigation season winding down, water managers and late-season users should monitor delivery schedules closely as canal operators begin transitioning toward season-end operations. Reservoir storage data, 7-day forecast details, and late-season delivery risk analysis are available in the full brief.

Snowpack Conditions

All monitored SNOTEL stations serving Caribou County's watersheds show seasonal baseline conditions for late September, with snowpack accumulation not yet underway in a meaningful way.

| Station | SWE | Snow Depth |

|---|---|---|

| Bear River RS | 0.0" | 0.0" |

| Emigrant Summit | 0.1" | 0.0" |

| Franklin Basin | 0.0" | 2.0" |

| Garden City Summit | 0.0" | 0.0" |

| Giveout | 0.1" | 0.0" |

| Slug Creek Divide | Data collection issues | — |

| Tony Grove Lake | 0.0" | 0.0" |

| USU Doc Daniel | 0.0" | 0.0" |

At this point in the calendar, 0.0" SWE is the expected condition — the seasonal median for these stations in late September is also effectively zero, so current readings do not indicate a below-normal anomaly for today's date. Franklin Basin's 2.0" snow depth with 0.0" SWE likely reflects early, low-density surface snow with negligible water content. Emigrant Summit and Giveout each show 0.1" SWE — trace accumulations consistent with early-season weather events rather than meaningful storage.

The important 2026 context belongs here: this year's snowpack melted out approximately 4–6 weeks ahead of the historical median meltout date, driven by an anomalous heat event in March. That early meltout shaped the summer supply picture. Slug Creek Divide data collection issues represent a monitoring gap for one station — users dependent on that station's readings should contact NRCS for status updates.

New accumulation season has not materially begun. The basin will remain dependent on existing reservoir carryover and baseflows until mountain snowpack builds and begins contributing meaningful SWE readings, typically by November.

Streamflow Conditions

Ten USGS gauges are active across Caribou County's four watersheds, showing a range of current conditions.

Bear River Basin:

The divergence between Pescadero (falling, 379 cfs) and Corinne (rising, 709 cfs) is the notable Bear River mainstem signal this week. Several tributaries — Little Bear River and Logan River — are rising, which likely accounts for volume gains in the lower system. The upper Bear River entry at Border, WY (71 cfs, rising) shows modest but improving inflow from Wyoming. Blacksmith Fork is stable at 47 cfs.

The Malad River reading of 6 cfs dated May 15 is flagged as unreliable for current use — it is more than four months stale. Users relying on Malad River conditions should contact USGS or IDWR for current status.

Blackfoot River Basin:

Inflow to Blackfoot Reservoir is modest at 17 cfs but trending upward. Late-season inflows at this level are typical as summer demand subsides, though the rising signal warrants monitoring for users tracking reservoir recovery heading into the carryover period.

Portneuf River Basin:

The Portneuf is rising at 67 cfs, a relatively healthy late-season reading for this system.

Salt River Basin:

Salt River inflow is stable at 405 cfs — a solid late-season reading for this system, indicating consistent inflow to upstream storage heading into the off-season carryover window.

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: Idaho Department of Water Resources (Eastern Regional Office in Pocatello, (208) 525-7161, for Bear River basin counties)

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, U.S. Bureau of Reclamation (for Blackfoot Reservoir), and PacifiCorp/Bear River Commission (for Bear Lake storage) for regulatory decisions and water rights administration.