Click here to read the report. Here’s the executive summary:
Rivers are crucial to supporting biodiversity and providing ecosystem services such as clean drinking water and recreation opportunities, offering far more value to people, wildlife, and ecosystems than might be expected given their small global footprint. Yet rivers are under increasing threat as the climate warms and our populations grow, placing greater stress and demand on freshwater resources. Despite their life-giving importance, few rivers and streams are currently protected from human impacts to their integrity and flow. We have the opportunity now to protect more of these waterways in the United States through a variety of mechanisms.
We offer a rigorous assessment of wild rivers that are currently unprotected and, using various criteria for evaluating their ecological value, quantify and highlight those that are most ecologically important to protect. We focused in particular on identifying rivers and streams throughout Colorado with the highest potential for Outstanding National Resource Water (ONRW) designation, although we anticipate the data provided to be valuable for supporting river protection through other mechanisms, such as the federal Wild and Scenic Rivers Act. Here, we connect designation criteria to statewide data to identify rivers with the greatest potential to achieve formal protection via ONRW designation. We summarize our key findings and map these rivers statewide to help visualize the “best of the best” river segments and other ecologically important places to seek new protections.
Our assessment shows that, of the 15,221 miles considered, rivers and streams with the highest ONRW potential are distributed widely across western Colorado, while most rivers east of the Front Range do not achieve sufficient water quality to be considered further for ONRW designation. In all, 662 river miles demonstrate outstanding overall value in that they score in the top 25% of all rivers statewide for every ONRW criterion, including water quality, ecological significance, recreational value, and absence of human modification, attributes that do not coincide as strongly elsewhere. It is important to note that Colorado requires water quality data for potential designation; unmeasured rivers and streams were excluded from consideration. Colorado’s rivers support a variety of aquatic species identified by the state as Species of Greatest Conservation Need (SGCN); 1,881 river miles are within the ranges of at least five aquatic SGCN. An impressive 12,600 river miles across western Colorado have sufficient water quality to support all beneficial uses, including drinking water; protection of any of these waters would help to maintain provision of this vital ecosystem service for generations to come. At the watershed level, the headwaters of the Dolores River are extraordinary in representing the greatest total river miles with high ONRW potential in a single watershed.
In short, thousands of river miles across Colorado—western Colorado, in particular—possess a wide range of ecological values and ecosystem services worthy of protection, whether through state-level designations, federal Wild & Scenic designation, or other available mechanisms. This assessment and the data accompanying it offer scientifically grounded support for identification of the values associated with rivers, streams, and watersheds across Colorado that can inform and support efforts to ensure those values persist.