Over the summer, areas of Colorado’s rivers have faced closures and fish kills due to weather conditions, but the Blue River in Summit County has managed to avoid negative impacts from monsoonal moisture and warm temperatures.
According to the most recent data from the United States Geological Survey, temperatures for the Blue River below Dillon Reservoir have consistently stayed between 44 and 44.5 degrees Fahrenheit for the past week. Kendra Fuller, executive director of the Blue River Watershed Group, said that as a headwaters location, the Blue River is going to have consistently cold water.
“There should be seasonal changes, and those seasonal changes of temperature trigger lifecycles in the river,” she said. “So the Blue River is naturally supposed to be pretty cold most of the year because our snowpack is the dominant funder of our river flow. We should see really cold temperatures in the winter. We’ll have a little bit of seasonal fluctuation as it warms in the summer with sun because we do get our runoff. It’s still cold, and it should remain cold, but it’ll get slightly warmer in the summertime than in the wintertime.”
However, there are parts of the Blue River that are under a 303(d) rule, which “requires states to submit to the U.S. Environmental Protection Agency a list of waters for which technology-based effluent limitations and other required controls aren’t stringent enough to implement water quality standards,” according to the Colorado Department of Public Health and Environment.
Temperatures have stayed on par with the average of the last 20 years — 83 degrees being the high — but Fuller said that lower parts of the Blue River struggle the most with high temperatures. Across the state, warmer river temperatures have had negative impacts on ecology and businesses that rely on the river. Throughout August, the Yampa River in Steamboat Springs faced on and off closures, including ones for tubing and commercial outfitters. At the time, water temperatures exceeded 75 degrees four days in a row, including a peak of 76.5 degrees on Aug 1.
“The lower Blue below Green Mountain Reservoir is listed as a state exceedance for temperature, so the Green Mountain Reservoir does not have the same benefit of cold water that the Dillon (Reservoir) does,” Fuller said. “We do have temperature challenges and state exceedances, meaning that it’s too warm for the fish to survive and thrive.”
This summer in Summit County has certainly been a rainy one, according to data from the National Weather Service in Boulder. In Breckenridge, this past July topped out at 2.74 inches, and in Dillon there was 3.47 inches of precipitation in August, breaking the record for most rain in August since 2000.
In Eagle County, a fish kill event took place in the Eagle River, just downstream from Wolcott, and it has been attributed to mudslides and erosion on banks of a number of tributaries to the Eagle River, including Milk Creek, Rube Creek and Alkali Creek.
“We have not had a large burn in the county, so we don’t have these big sediment piles that are exposed,” Fuller said. “We’ve got pretty good vegetation on our slopes, and that’s really saving us. We have not seen the flows that we should really see because of all of the rain — because we’d have diversions in our rivers — even though we’ve had a significant amount of rain. We don’t have an increase in the flows of our rivers very much because so much is diverted to the Front Range.”
According to Zach Hiris, a meteorologist at the National Weather Service in Boulder, this upcoming weekend, Sept. 8-12, will continue to be warmer but unlikely to break any heat records. This week in Summit County will be dry as well, which prompted fire danger to be increased from low to moderate. Warmer temperatures, lower humidity levels and increases in wind speeds have lowered the fuel moistures, according to Jay Nelson, deputy chief of the Red, White & Blue Fire Protection District.
“A cold front associated with the northern trough axis should push through sometime Friday or Saturday, bringing temporary relief to the heat,” Hiris said.
