2026 brought exceptionally low snowpack to the Colorado Headwaters, with Snow Water Equivalent (SWE) reaching record-low levels during the spring. In the graph below, Compare 2026 (black line) with the historical range.

Snow Water Equivalent in Colorado Headwaters

The gauges on the Blue River, Snake River, and Tenmile Creek upstream of Dillon Reservoir show how much water is naturally reaching the reservoir from the mountain watershed. Flow measurements from upper-watershed gauges are approaching record lows from 2002, or have established new record-low flows.

Blue River at Blue River Streamflow

During drought, reduced snowpack and runoff prevent reservoirs from refilling, while continued water use and releases draw down stored water. Dillon Reservoir is Dillon Reservoir is at approximately 67% of its 257,304 acre-foot capacity.

In the following graph contrasts the amount of water stored and recharged in Dillon Reservoir in an average year (dotted green line) with the draw down occurring in 2026 (solid black line).

Dillon Reservoir Storage

Three stream gauges monitor flows between Dillon Reservoir and Green Mountain Reservoir, and all three tell the same story: streamflows have been historically low in 2026.

1. Blue River below Dillon Reservoir: This streamgage measures water leaving the reservoir and entering the downstream Blue River. With exceptionally low snowpack and runoff in 2026, water managers are carefully managing releases from Dillon Reservoir to conserve storage and stretch limited supplies through the remainder of the drought. Releases are within 5 CFS of the record low flow rate.

• Average flow – 142 CFS
• 09/11/26 flow – 53.9 CFS
• Minimum Release Flow Rate – 50 CFS

2. Elliot Creek Feeder: This streamgage measures water delivered to Green Mountain Reservoir through the Elliott Creek Feeder. The feeder was built as part of the Colorado-Big Thompson Project to divert water from Elliott Creek into Green Mountain Reservoir.

• Average flow – .49 CFS
• 09/11/26 flow – RECORD LOW .06 CFS

3. Straight Creek below Laskey Gulch: Straight Creek flows into the Blue River between Dillon and Green Mountain Reservoirs. Streamflow is just .37 CFS above the historic minimum.

• Average flow – 7.9 CFS
• 09/11/26 flow – 2.97 CFS
• Historic minimum – 2.6 CFS (2002)

Green Mountain Reservoir is an important downstream point of storage in the Blue River system. Tracking its elevation shows how much water is being stored before releases continue downstream toward the Colorado River.

The drought has caused unprecedented impacts to Green Mountain Reservoir which normally provides an important reserve called the Historic Users Pool (HUP). The HUP protects hundreds of Western Slope agricultural, municipal, and domestic water users from curtailment. For the first time since the HUP was established, extremely low snowpack and runoff prevented the pool from fully filling, forcing water managers to use Williams Fork and Wolford Mountain reservoirs to provide releases for the Grand Valley.

The graph below contrasts Green Mountain Reservoir's average pool elevation (dotted green line) compared to the 2026 pool elevations (solid black line).

Green Mountain Pool Elevation (feet)

Streamflow below Green Mountain Reservoir shows how much water is moving downstream to the rest of the Colorado Basin after reservoir storage and management.

As a result of the drought, Green Mountain Reservoir has had to draw on stored water to meet downstream obligations and water needs. Although streamflow below the reservoir remains within the “normal” percentile range, those flows are being sustained by releases from storage despite limited inflows.

The Colorado River is also experiencing exceptionally low flows. USGS streamgages from Kremmling downstream through Dotsero, Glenwood Springs and Cameo are recording historically low conditions this year. Together, these gages show that low flows extend well beyond the Blue River watershed and across a broad section of the Colorado River in western Colorado.