WATER QUALITY IMPACTS FROM THE WEST FORK COMPLEX FIRE: MONITORING ECOSYSTEM HEALTH AND IMPACTS ON DOWNSTREAM COMMUNITIES IN THE UPPER RIO GRANDE

Forest fires affect water quality in the disrupted watershed, which can devastate the aquatic ecosystem including sensitive trout (Salmonidae) and macroinvertebrate species. The West Fork Fire Complex consumed 110,000 acres of forest in the state of Colorado during the summer of 2013. Damage to the soils was of moderate to high severity in the majority of the area (60%). The fire surrounded the Rio Grande and caused several hillslope failures affecting water quality and habitat critical to insects and fish. The water quality and quantity of the Rio Grande (above and below the burn) and some of the effected tributaries are currently being monitored with a range of in situ and real-time water sensors. Parameters important to the survival of aquatic life and water supply, such as flow, temperature, dissolved oxygen, pH, conductivity, total dissolved solids, and turbidity are being measured real-time. Other water quality characteristics such as metals, nutrients, and total suspended solids are also monitored bi-monthly. Macroinvertebrate and fish populations are sampled in the same locations annually. Three years of observations showed the ecosystem to be relatively resilient, with stable water quality and survival of insects and fish. However, intense monsoon seasons continue to drive extensive sediments into upstream tributaries from steep, severely burned hillslopes. These monsoon events have caused acute and dramatic fish kills, where hundreds of trout were reported killed in one tributary in a single day event. One component of the study includes development of a classified GIS risk map that displays the ranges of soil loss across the watershed to identify areas that are likely to contribute sediment loads to the Rio Grande. The developed map can then be used by resource managers to protect roads, properties, fish ecosystems and other valuable resources from potential hillslope failure. This presentation will highlight this ongoing work to better understand post-fire impacts on Colorado ecosystems and protect important natural resources.