The regulation and control of the flow of water in the Santa Fe river, the prevention of pollution thereof, the preservation of the trees and other growth along the shores of said stream, from the Denver & Rio Grande railroad bridge to the Canon Road bridge on Palace avenue, within the city of Santa Fe, and a comprehensive and systematic development of such portion of said river and its banks as a park system, are hereby declared to be proper objects of state encouragement and support, as tending to improve the capital city of the state and the capitol buildings and grounds.