Eagle River: Avon WWTP to Squaw Creek

Current and Historical Drivers of Degradation

Although this segment is not listed as an impaired waterway by Colorado’s Water Quality Control Division, macroinvertebrate health indices in Avon hover only slightly above the state of Colorado’s impairment threshold and are consistently lower than sites both upstream and downstream. Indices of sensitive taxa presence are the lowest of anywhere on the mainstem Eagle River, indicating degraded water quality conditions. Ambient nutrient concentrations do not exceed standards but are regularly within 50% of the standard value. Water quality impacts are likely sourced from urban runoff in the vicinity of Avon. Disruption or destruction of the riparian corridor from urban and suburban development likely also plays a significant role.

Flows are altered on this reach by upstream water use and management. The frequency of peak flows equivalent to the natural 1-in-4 year flood declined more than 40%. Peak flows during dry years declined 20%. Total annual flow volumes in dry years declined 26% when compared to natural historic conditions.

Report Card