Colo. Rev. Stat. § 31-25-509
At the time of ordering the construction of district sanitary or storm sewers or at any time thereafter, the construction may be ordered in like manner in subdistricts, in such manner as to connect the subdistricts, or such part thereof, with the district sanitary or storm sewer for the purpose of sanitary or storm drainage. The cost of subdistrict sanitary or storm sewers in each subdistrict or part thereof, with the appurtenances, may be assessed upon all the land in the subdistrict or in the part improved in proportion as the area of each piece of land in the subdistrict or in the part improved is to the area of all the land in the subdistrict or in the part improved exclusive of public highways. Combined sewers for sanitary and storm drainage may be authorized and constructed in the same manner as provided for the construction of sanitary or storm sewers and the cost thereof assessed in the same manner and proportion.
C.R.S. § 31-25-509
(1) This section is similar to former § 31-25-529 as it existed prior to 1975.
(2) This section was originally numbered as § 31-25-508 in House Bill 75-1089 but was renumbered on revision in 1977 for ease of location.