Flow-Adjusted Trends in Dissolved Selenium Load and Concentration in the Gunnison and Colorado Rivers near Grand Junction, Colorado, Water Years 1986-2008.

摘要

Selenium impairment of stream segments from nonpoint sources in western Colorado is of concern to local, State, and Federal governments, local water providers, and local land users. As a result of elevated selenium concentrations, many western Colorado rivers and streams are on the U.S. Environmental Protection Agency (EPA) 2010 Colorado 303(d) list, including the main stem of the Colorado River from the Gunnison River confluence to the Utah border. The term 303(d) list refers to the list of impaired and threatened streams, river segments, and lakes that all States are required to submit for EPA approval every 2 years. The States identify all waters where required pollution controls are not sufficient to attain or maintain applicable water-quality standards. Selenium is a trace element that bioaccumulates in aquatic food chains and can cause reproductive failure, deformities, and other adverse impacts in birds and fish, which may include some threatened and endangered fish species native to the Colorado River. The Colorado River along with portions of Colorado River tributaries in the Grand Valley of western Colorado located within the 100-year flood plain of the Colorado River are designated critical habitat for four fish species listed under the Endangered Species Act--the Colorado Pikeminnow, Razorback Sucker, Bonytail, and Humpback Chub.