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Recent debris flows cause die-off of fish, crayfish in Nottingham Lake

Debris from the Avon mudslides has impacted the lake’s oxygen levels

A die-off of crayfish and fish in Nottingham Lake can be attributed to recent mudslides and debris flows in Avon.
John LaConte/JLaConte@vaildaily.com

The impacts of the July 22 flash flooding and subsequent mudslides are continuing to manifest in Avon, this time for the species living beneath the surface of Nottingham Lake.

In recent days, Avon residents and visitors may have noticed an increase in dead or dying fish and crayfish in the lake.

According to Drew Isaacson, the town of Avon’s public works superintendent, the town has seen an abnormal number of dead fish in the lake following the July 22 event.



“Unfortunately, the flash flooding brought with it debris flows that are having a negative impact on our waterways. Sediment from erosion will decrease dissolved oxygen levels in the water as a result of decomposing organic matter and this unfortunately does lead to fish die-off,” Isaacson wrote in an email to the Vail Daily.

There has also been a notable number of the lake’s crayfish coming to the surface to get oxygen, something that is “not an option for fish,” he wrote.

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However, even with this option, Isaacson noted that the crayfish “don’t seem to have been completely spared by this event and quite a few have died.”

Eric Heil, the Avon town manager, noted that the town does regularly conduct E. Coli testing in the lake but has seen no toxicity or bacteria issues.

Each year, the town stocks Nottingham Lake with thousands of catchable fish. And while officials have noticed impacts from the mudslides, Isaacson estimated that only a “single-digit percentage of the fish in our lake” have died as a result.

While the crayfish are not stocked in the lake, there is a sizable population of the species that exist, which the town monitors to ensure they are native and not invasive species.

Isaacson noted that the town is planning to call on the expertise of Colorado Parks and Wildlife to help resolve the matter. In the meantime, he wrote that public works has been working diligently to clear the mud and debris from irrigation ditches “in an attempt to divert more water into the lake, which should increase dissolved oxygen levels.

With most of Eagle County still experiencing severe to extreme drought conditions, water temperatures are another concern for many of the area’s waterways. However, Isaacson doesn’t feel that those are a contributing factor here.

“Water temps are a major concern in our aquatic ecosystems this time of year, but don’t appear to have been a contributing factor, outside of the possibility of creating turnover in the lake due to a temperature gradient created from the influx of cool floodwaters being introduced,” he wrote.

Isaacson added that, according to the Eagle River Watershed Council’s water temperature gauges for local rivers and streams, that since the flooding, the Avon area has seen a decrease in river temperatures.


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