Colo. Rev. Stat. § 31-12-310
When in pursuance of this part 3 any city or town is annexed to any city existing under a special charter, all rights, causes of action, records, uncollected revenues, and other property of the city or town so annexed shall accrue to and become the property of the annexing city. At least a proportionate share of the moneys of the annexing city available for water service, lights, and other public improvements shall be expended each year within the area formerly included within the city or town so annexed, based upon the valuation for assessment thereof. The water and light service of any city or town so annexed shall not be curtailed after such annexation.
C.R.S. § 31-12-310
This section is similar to former § 31-8-208 as it existed prior to 1975.