Larimer County Water Intelligence Brief

August 17, 2026 | Free-Tier Edition

*Cache la Poudre & Big Thompson Corridors | C-BT System | Water Division 1*

Situation Summary

Larimer County's two-river system — the Cache la Poudre and Big Thompson — is operating on late-summer baseflows following an anomalous 2026 season in which mountain snowpack melted out 4–6 weeks ahead of the historical median meltout date across all five headwater SNOTEL stations. In-county storage at Horsetooth Reservoir and Carter Lake, along with C-BT transbasin deliveries via the Adams Tunnel, remain the primary supply buffer for both agricultural irrigators and Fort Collins and Loveland municipal users through the remainder of the irrigation season. Reservoir storage data and 7-day forecast details are available in the full brief.

Snowpack Conditions

All five SNOTEL stations monitoring Larimer County's headwaters report conditions consistent with normal late-summer meltout. Because the seasonal median SWE for mid-August is also 0.0" at each of these stations, current readings reflect expected seasonal conditions — not below-normal snowpack relative to today's date. The supply story for 2026 is defined by *when* meltout occurred, not by current SWE deficits.

Big Thompson headwaters (Rocky Mountain National Park corridor, HUC 10190006):

Cache la Poudre headwaters:

Across both corridors, the pattern is uniform: snowpack is gone. The trace SWE readings at Willow Park, Bear Lake, and Hourglass Lake likely reflect residual soil moisture or instrument sensitivity rather than meaningful stored snow. The operational significance of the 2026 season is that meltout occurred 4–6 weeks ahead of the historical median meltout date, compressing the spring runoff pulse into late March and April and reducing the window for reservoir fill and stream recharge ahead of peak irrigation demand. No new snowpack contribution to streamflow should be anticipated for the remainder of the summer.

Streamflow Conditions

Larimer County's two river systems are reporting notably different late-summer flow profiles, with both Poudre gauges showing a rising trend that warrants attention.

Big Thompson River:

At 81 cfs, the Loveland gauge reflects combined native Big Thompson flow and any C-BT releases passing through Olympus Dam and the Loveland agricultural reach. The stable trend suggests delivery conditions are currently holding steady. Irrigators drawing from the Big Thompson corridor below Lake Estes should monitor Northern Water's delivery announcements for any adjustments to C-BT release scheduling as late-season demand continues.

Cache la Poudre River:

Both Poudre gauges are rising — an noteworthy signal in mid-August when flows typically trend low or stable under summer baseflow conditions. The Fort Collins gauge at 7 cfs reflects in-town conditions influenced by municipal diversions and Fort Collins Utilities operations; the Timnath gauge at 13 cfs captures aggregate flow including Fort Collins municipal return flows, which augment the lower Poudre agricultural reach. The rising trend at both stations should be verified against local precipitation or operational discharge sources before drawing conclusions. Senior water rights holders on the Poudre — where priority dates extend to the 1860s and 1870s — should coordinate with Water Division 1 regarding current administration conditions. The Cache la Poudre's Wild and Scenic River designation through the canyon reach constrains new diversion infrastructure, making streamflow management at existing points of diversion especially critical in tight late-season conditions.

Seasonal Guidance

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

Data Sources: SNOTEL data through August 16, 2026; USGS streamflow data through August 17, 2026

Data Current As Of: August 17, 2026; administrative context via Colorado Division of Water Resources

Important Disclaimers: This brief provides automated analysis for informational purposes only. Specific numerical claims have not been independently verified. Consult official sources including Northern Colorado Water Conservancy District (Northern Water — headquartered in Berthoud, Larimer County; 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.