Larimer County Water Intelligence Brief

Agricultural & Municipal Water Supply | September 28, 2026

*Free-Tier Edition*

Situation Summary

Both the Cache la Poudre and Big Thompson rivers are running at late-season low flows this week, with the Poudre showing a mixed signal — rising at Timnath while falling at Fort Collins — and the Big Thompson at Loveland sitting at 29 cfs and falling, reflecting the tail end of the irrigation season across both corridors. For Larimer County irrigators on alfalfa, hay, and corn acres east of Fort Collins and in the Loveland-Berthoud reach, these flow levels signal that late-season delivery margins are thin and supply reliability through October will depend heavily on stored water in Horsetooth Reservoir and Carter Lake — Larimer County's own in-county C-BT storage facilities. Reservoir storage data, 7-day forecast details, and delivery outlook analysis are available in the full brief.

Snowpack Conditions

All five NRCS SNOTEL stations monitoring Larimer County's two river systems are showing the expected end-of-season snowpack picture for late September. Bear Lake (9,490 ft, Big Thompson headwaters) recorded 0.1" SWE with 0.0" snow depth on September 27. Willow Park, the second Big Thompson headwaters station, is experiencing data collection issues and no reading is available. On the Cache la Poudre side, Joe Wright recorded 0.2" SWE with 1.0" snow depth — the highest SWE reading across the network — while Deadman Hill showed 0.0" SWE with 1.0" depth, and Hourglass Lake recorded 0.0" SWE and 0.0" depth.

Where percent-of-median figures are not shown for a station, the median SWE for this date is also 0.0" — meaning these stations are at a normal seasonal condition for late September, not anomalously low at this moment in the calendar. The meaningful 2026 snowpack story is one of timing: an anomalous March heat wave caused mountain snowpack across both the Big Thompson and Poudre headwaters to melt out 4–6 weeks ahead of the historical median meltout date, compressing spring runoff and reducing total seasonal delivery volumes well before summer demand peaked.

Streamflow Conditions

The Big Thompson River at Loveland is flowing at 29 cfs and falling as of September 28, reflecting typical late-season recession on the lower Big Thompson agricultural reach below Olympus Dam. This gauge captures both native Big Thompson flow and any C-BT releases moving through the system, making it the primary indicator for irrigators drawing from the Big Thompson corridor in the Loveland area.

On the Cache la Poudre system, the Fort Collins gauge is reading 10 cfs and falling, while the Timnath gauge above Boxelder Creek is reading 9 cfs and rising — a divergence worth noting, as rising flow at Timnath while Fort Collins falls may reflect Fort Collins municipal return flow dynamics and localized delivery patterns on the lower Poudre. Both readings represent low late-season flows consistent with end-of-irrigation-season conditions. Senior water rights holders on both rivers — some dating to the 1860s and 1870s — should monitor Division Engineer communications as flows continue to recede.

Seasonal Guidance

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Data Sources: SNOTEL data through September 27, 2026; USGS streamflow data through September 28, 2026.

Data Current As Of: September 28, 2026. Water rights administration status reflects Colorado Division of Water Resources records.

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, Northern Colorado Water Conservancy District (Northern Water — headquartered in Berthoud, Larimer County; administers C-BT Project; Horsetooth Reservoir and Carter Lake data via northernwater.org or USBR HydroMet site HRT), City of Fort Collins Utilities, and Colorado Division of Water Resources Water Division 1 (Greeley office) for regulatory decisions and water rights administration.