You are here

Severe wildfire has long-term consequences for stream water quality

Date: September 24, 2018

Fifteen years after the Hayman Fire, watersheds with extensive high-severity wildfire still had elevated levels of streamwater nitrogen


Background

Vegetation recovery has been slow at the Hayman Fire burn site
Vegetation recovery has been slow at the Hayman Fire burn site. (Photo: O. Rhoades)
Rocky Mountain Research Station (RMRS) scientists began to evaluate this question following the 2002 Hayman Fire, located 50 km southwest of Denver.  The Hayman Fire, the largest in recorded Colorado history, burned watersheds with streams that flow into the South Platte River, affecting the drinking water supply for residents of the Denver Colorado metropolitan area as well as agricultural and industrial users.

Fortuitously, RMRS scientists and USFS managers began to analyze stream water quality in tributaries of the South Platte River prior to the fire, so were able to evaluate the short-term effect of the fire on nutrient, sediment and stream temperature and more recently to track the fire’s long-term effects.   

Key Findings

  • Almost 15 years after the Hayman fire, watersheds with extensive high-severity wildfire still had elevated levels of streamwater nitrogen; elevated stream carbon was found in watersheds with more moderate-severity burn area. 
  • The persistent, elevated nitrogen and carbon in burned watersheds are not a threat to drinking water quality, but they exceed expected levels for healthy reference streams in this region.
  • However, the extensively burned watersheds no longer act as strong nitrogen “sinks” that retain more than 90 percent of atmospheric nitrogen inputs, as they did prior to the fire.
  • Future recovery remains uncertain. Post-fire forest recovery has been extremely slow and may require another several decades or longer.

Related Publication

Rhoades, Charles C.; Chow, Alex T.; Covino, Timothy P.; Fegel, Timothy S.; Pierson, Derek N.; Rhea, Allison E. 2018. The legacy of a severe wildfire on stream nitrogen and carbon in headwater catchments. Ecosystems. doi: 10.1007/s10021-018-0293-6.



Principal Investigators: 
Forest Service Partners: 
Pike National Forest
External Partners: 
Alex Chow, Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC;
Timothy Covino and Allison Rhea, Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO;
Derek Pierson, Department of Crop and Soil Science, Oregon State University, Corvallis, OR