August Watershed Snapshot: Hot and Dry

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.

Fly fishing should be avoided in areas with elevated water temperatures and low flows, especially during the heat of the day around 2pm.


Low flows and high temperatures were the norm for most of the watershed, with temperatures in excess of 68°F/20°C recorded in the lower Fraser Valley and on Muddy Creek. Popular fishing spots with elevated water temperatures pose a serious danger to trout already stressed from the warmer waters, where the additional stress of being caught can often be deadly. A popular fly fishing spot on a newly restored reach of the Fraser River, just above the confluence with Ranch Creek, experienced water temperatures above 68°F/20°C on 21 days out of the previous month, posing a serious danger to trout.

With so many days exceeding healthy temperatures for fish in the past month, closing certain areas to fishing would provide fish with enough safety to rest in cooler waters during the hottest time of the day and year. However, fishing closures come with a significant cost, as tourism from fishing these popular areas is a key part of the local economy. Yet we need to be asking ourselves: if we continue to make life hard for fish populations in these vulnerable areas now, how much longer into the future can we sustain tourism that is dependent on a healthy fishery?


How you can help preserve our watershed:

  • Voluntarily fish in areas with cooler water, such as areas below dams and streams at higher elevations.
  • Carry a thermometer with you when you go fishing. If the water temperature is near or above 68°F/20°C, STOP FISHING.
  • Spread the word on how high temperatures are dangerous, and eventually deadly, for trout in our area. We can protect our fishery if we take care of it together.

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