From Gold Mining to Gold Medal Fishery: Evaluating the Fishery Response to Stream Restoration on the Upper Arkansas River, Colorado

Abstract

AbstractOver a century of metals pollution and channel disturbance associated with historical mining, land use, and water development contributed to degradation of aquatic and riparian habitat within the upper Arkansas River watershed near Leadville, Colorado. Following water quality remediation, habitat restoration was conducted for a 17.7‐km reach characterized as an overwide channel that lacked velocity refuge and overwinter habitat for salmonids. The primary goals of restoration were to improve populations of Brown Trout Salmo trutta and individual fish health, with a target to increase fish metrics by 10% within 5 years after restoration. Fish metrics included Brown Trout density, biomass, quality, and relative weight, where quality was defined as the density of Brown Trout over 356 mm in length. Changes in all fish metrics were evaluated with a before‐after–control‐impact study design that utilized five control sites and five impact sites. Biomass was the only metric that exhibited a significant interaction between site type and period (before and after), with increases of 12% and 21% at control and impact sites, respectively. Increased density (10%) and relative weight (2.4%) were observed across all sites regardless of type. Changes at individual sites were less evident, with only one impact site showing significant increases in biomass (99%) and quality Brown Trout (306%). These results suggest that Brown Trout populations within the upper Arkansas River have continued to improve following large‐scale water quality remediation and stream restoration efforts. Additional monitoring is recommended to evaluate long‐term trends and inform adaptive management.