It has been represented by Democrat Janice Marchman since 2023.

Prior to redistricting the district was represented by Republicans Rob Woodward and Kevin Lundberg.

[3][4] District 15 covers nearly all of Larimer County outside of Fort Collins, including the communities of Loveland, Estes Park, Berthoud, Wellington, and Laporte.

[6] Colorado state senators are elected to staggered four-year terms; under normal circumstances, the 15th district holds elections in midterm years.

The 2022 election will be the first held under the state's new district lines.