August Watershed Snapshot: Hot and Dry

By | UCRWG Updates, Watershed Snapshot | No Comments

Colored dots at monitoring locations reflect stream flow levels, with blue and green dots indicating water levels well above average and red and yellow dots marking water levels well below historic flows. Crosses within the dots show water temperature, while the red numbers next to selected locations show the number of days with water temperatures above 68°F/20°C from July 13th – August 13th.

The UCRWG August Snapshot looks at stream flows and water temperatures across Grand County, with a focus on the number of high water temperature days over the previous 31 day period.

Flows were low throughout much of the Upper Colorado River basin when we took our monthly snapshot on August 14th, with ongoing drought conditions and high temperatures in July and August elevating stream temperatures throughout much of the watershed and state of Colorado. Elevated flows released from Lake Granby were reflected in the Colorado River west of Kremmling, with higher water volumes keeping temperatures just below the 68°F/20°C mark for fish downstream.

Cooler waters on Muddy Creek just below Wolford Reservoir are marked by the green cross just north of Kremmling, where temperatures were within the safe zone for trout, though overall flow levels were still lower than normal.  The benefits of extra water released on the Colorado River near Pumphouse can be seen by the blue dot just southwest of Kremmling, where flows are elevated in an effort to protect endangered fish much further down the Colorado River. While the extra water lowers temperatures a bit, waters are still warm enough to stress trout.  Stream temperatures in excess of 65°F/18°C stress native trout adapted to cooler waters, while waters above 70°F/21°C result in trout having difficulties using oxygen.

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July Watershed Snapshot: High Temperatures and Fish Stress

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Upper Colorado River Watershed Snapshot: July 17, 2020

Flow levels and water temperatures taken from USGS flow gauges around the Upper Colorado River watershed.

 

Water temperatures were high across most of the Upper Colorado River Watershed in July,

with low flows in key parts of the watershed from trans-basin diversions. Over 500 cubic feet per second (CFS) were diverted to the Front Range through the Moffat and Adams tunnels, marked by the purple lines on the right side of the map.

Flows at Windy Gap represent water sent further downstream, with only 176 cfs flowing further down the Colorado in mid-July. The red dot to the left of Granby marks Windy Gap Reservoir, where the two major confluences of the Upper Colorado River – the North Fork and the Fraser – meet.

Green plus signs mark areas in the watershed with lower water temperatures, where fish won’t already be stressed by water conditions, while the yellow and red crosses on the map mark areas in the watershed that should only be fished in the morning, before the heat of the day, or not at all.

Knowing water temperatures is key when it comes to fly fishing. Trout are cold water fish, which means they experience stress at higher water temperatures. Catch-and-release fishing on a stream or waterway with elevated temperatures can kill trout already stressed from the warm waters.

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June 2020 Watershed Snapshot: Peak Flows and Climate Change

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Upper Colorado River Watershed Snapshot: June 4, 2020

Drawing from data recorded on USGS gauges located around the Fraser Valley, this map compares measurements from June 4th with median flows from previous years.

The Upper Colorado River watershed experienced peak flows for the year on June 4, hinting that the impacts of climate change are already being felt in the Fraser Valley.

Predicted impacts from climate change in the Upper Colorado River watershed include:

  • Higher than average runoff earlier in the spring
  • Peak run off occurring in May rather than June
  • Lower than average runoff and reduced groundwater levels into the late summer and fall months.

In general, flows were well above average in early June, with the most pronounced flows in the upper reaches of the watershed marked by blue dots. Further downstream, green dots mark flows only slightly above average.

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Watershed Snapshot

By | UCRWG Updates, Watershed Resiliency Plan, Watershed Snapshot | No Comments
UCRWG is excited to release our first-ever Upper Colorado River Watershed Snapshot, providing real-time modeling of stream flows in the Upper Colorado River watershed for August 1, 2018. This is a crucial first step in locally-based watershed modeling, allowing for a watershed-scale perspective on how water demands from both the Eastern and Western slopes are putting stress on the headwaters of the Upper Colorado River.

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