Colo. Rev. Stat. § 37-47-129
The board of directors of said district may invest any surplus funds of the district including any funds in the construction fund assessment not needed for immediate use to pay the cost of construction of any project in any one of the subdistricts, or to pay bonds or coupons or to meet current expenses, in securities meeting the investment requirements established in part 6 of article 75 of title 24, C.R.S. The board of directors of said district may require any funds of the district, or of any subdistrict, to be deposited with such depository or bank as may be designated by the board and likewise shall have authority to require the treasurer of the district to take from such depository a bond with corporate surety to insure payment of any such deposit or to require such depository to pledge securities of the same kind as those in which the district is authorized to invest its funds to insure payment of any such deposit.
C.R.S. § 37-47-129