• Boulder County Nature Association
• Broomfield Health and Safety First
• Center for Biological Diversity
• Clean Energy Action
• Colorado Green Voice
• ColoradoWild
• Culture In Place
• Earthwork Conservation Planning
• Ecological Consultants for the Public Interest (ECPI)
• Equinox Consultancy
• Karl Ford, Ph.D., Environmental Scientist (retired Bureau of Land Management)
• Grasslands Colorado
• Green Root Podcast
• Eco-Integrity Alliance
• John Muir Project
• Barry R. Noon, Professor, Department of Fish, Wildlife, and Conservation Biology, Colorado State University
• Peak to Peak Forest Watch
• PLAN-Boulder County
• Prairie Protection
• Save Boulder Parks and Trails
• Nicholas Scritchfield, Former Rocky Mountain National Park Ranger
• Rocky Smith, Forest Management Analyst
• Thomas T. Veblen, Distinguished Professor Emeritus, University of Colorado at Boulder
• Western Watersheds Project
• WildEarth Guardians

• Colorado Democratic Party
• Indivisible Colorado
• Indivisible NoCo
• League of Women Voters

Others That Publicly Oppose Prop 137: