Dave Powell, USDA Forest Service

Bark beetle kill causes increase in stream flow and affects water quality in Colorado 

Stream flows in watersheds with bark beetle infestation increase by about 30 percent, according to new research from the National Science Foundation, and can be connected to previous research that found an increase in carcinogenic disinfection by-products in water.

Trees affected by beetle infestations, which turn red and then gray, no longer absorb water from the ground for photosynthesis, a process called transpiration that leads to evaporation of that water. Since the infected trees are no longer absorbing the water from the soil, the water becomes part of the groundwater, which leads to an increase of water flow in nearby streams.

The National Science Foundation’s Water Sustainability and Climate Program funded the study of the two watersheds, Big Thompson and North Inlet, in Rocky Mountain National Park during late summer in 2012. Researchers indicated in their findings, published in the Nature Climate Change journal, that understanding these changes in water flow are important because it concerns water supply, water rights, impairment of riverine ecosystems and water quality concerns, such as the formation of disinfection byproducts in the watersheds.