District 4: Carl Castillo

Counties Served: Adams and Boulder counties
Term Ends: July 1, 2029

About Commissioner Castillo

Carl Castillo is a retired public policy attorney and advisor with over 30 years of experience in intergovernmental relations, transportation policy, land use, and environmental law. He spent over 20 years as Chief Policy Advisor and intergovernmental affairs lead for the City of Boulder, advising the City Manager and City Council on transportation, land use, regional planning, and other complex intergovernmental matters.

While there, he helped represent Boulder’s interests at the Northwest Mayors and Commissioners Coalition, a regional body that coordinates transportation investment priorities across Colorado’s northwest metro region. He also co-founded Colorado Communities for Climate Action (CC4CA), a coalition of 49 local governments across the state advocating for stronger state and federal climate policy. His work has focused on helping local governments navigate infrastructure, transportation, and regional policy challenges through coalition-building and intergovernmental collaboration.

Before joining Boulder, Castillo served as an attorney with the United States Environmental Protection Agency, handling civil and administrative enforcement of federal environmental law. That work gave him firsthand experience with how federal environmental requirements intersect with infrastructure projects.