Colorado River from Moab Rim.
More than half of the streamflow in the Upper Colorado River Basin originates as groundwater, according to a new USGS study. Groundwater and surface water are considered a joint resource.
The entire Colorado River Basin currently supports 50 million people, and that amount is expected to increase by 23 million between 2000 and 2030. On average, 90 percent of streamflow in the Colorado River Basin originates in the Upper Basin, which is the area above Lees Ferry, Arizona. This water has a multitude of uses that include irrigation, municipal and industrial purposes, electric power generation, mining activities, recreation, and supporting habitat for livestock, fish and wildlife.
Scientists used a new method to more accurately estimate the percentage of groundwater that supports streamflow. Researchers studied long-term records of water chemistry and streamflow data at 146 sites in the Upper Colorado River Basin in Colorado, Utah, New Mexico and Arizona. These data were then analyzed to create a model to predict and map where streamflow originates in the basin. On average, 56 percent of the streamflow in the basin originated from groundwater. Original public domain image from Flickr