Department 400 - Department of Natural Resources
- Division 401 - Executive Director of Department of Natural Resources (§§ 401-1-1 — 401-1-23)
- Division 402 - Division of Water Resources (§§ 402-1-1 — 402-17-A)
- Division 403 - Bureau of Mines (§ 403-1)
- Division 404 - Oil and Gas Conservation Commission (§§ 404-1-100 — 404-3)
- Division 405 - Colorado Parks and Wildlife (405 Series, Parks) (§§ 405-1-100 — 405-8-807)
- Division 406 - Colorado Parks and Wildlife (406 Series, Wildlife) (§§ 406-0-000 — 406-17-17174)
- Division 407 - Division of Reclamation, Mining and Safety (§§ 407-1-1 — 407-7)
- Division 408 - Colorado Water Conservation Board (§§ 408-1-1 — 408-3-15)
- Division 409 - Board of Land Commissioners (§§ 409-1 — 409-2)
- Division 410 - Ground Water Commission (§§ 410-1-1 — 410-2-14)