In 2013, the West Fork Complex Fire burned 110,000 acres in the Upper Rio Grande. The majority of the area burned moderately to severely, where vegetation was removed and the heat altered soils and increased the potential for erosion. A team of researchers from the Colorado School of Mines (CSM) partnered with RWEACT (Rio Grande Watershed Emergency Action Coordination Team) to evaluate the fire’s impacts on water quality, aquatic insects and fish.
This work seeks to better understand forest fire impacts on water quality and aquatic ecosystem in order to learn and prepare for future fires. The study is currently in its third year with CSM researchers still monitoring water quality, insects and fish populations along the Rio Grande and four of its tributaries. Overall, the Rio Grande appears resilient and remains healthy, though some segments continue to receive higher sediment loads and experience turbid water below the burn scar. When the water has been turbid on the main-stem of the Rio Grande, fish have been able to move away from areas with poorer water quality. Currently, trout populations continue to grow and achieve Gold Medal trout water status as designated by Colorado Parks and Wildlife in much of the Rio Grande. Insect populations in the Rio Grande suffered the initial after the fire but have now recovered.
A few of the Rio Grande’s tributaries were impacted more severely by the fire. Fish are unable to escape water quality impacts in smaller tributaries. Some of the fire-impacted tributaries experienced fish kills the summer of 2014 due to high sediment loads driven by monsoon rain events. Trout suffocate and die when exposed to suspended solid concentrations above 50 milligrams per liter for an extended time.
Initial water quality probes were installed in the fall of 2013; additional probes were installed and retrofitted to monitor a total of seven characteristics per probe. Data was remotely transmitted and field monitored through site visits.