C.R.S. § 31-30-101

The governing body of any city or town may provide by ordinance for a paid fire department, a paid police department, or a paid street department or all of same and may fix, define, and classify the various grades of employment in such departments, which grades and classifications shall be based upon the nature of the services to be rendered and the duties to be performed and shall also fix uniform wages and salaries to be paid to all employees in each particular class, which wages may be lowered or increased uniformly for each class from time to time.