The width, depth, course, and dimensions of said channel shall be as established by ordinance duly enacted by the council of the city and county of Denver, and said city and county has the power to acquire by purchase or condemnation all lands necessary to improve, straighten, widen, narrow, deepen, or extend said channel, and the public works department has exclusive control of the construction of said improvement.
C.R.S. § 30-11-205