Water rights law is very well established, with several different viewpoints. The one I'm most familiar with is the prior appropriation doctrine used in the western US, specifically, New Mexico.
Available water belongs to the public, not landowner. However, water use rights are assignable.
The right to use water goes first to the person with the oldest claim (the "senior appropriator"). You might have no claim to water running through your land, or as a junior appropriator only get access during wet years.
You may not block a senior appropriator from being able to make their appropriated beneficial use of that water.
As regarding pristine or pollution, quoting the NM constitution, 'The protection of the state's beautiful and healthful environment is hereby declared to be of fundamental importance to the public interest, health, safety and the general welfare. The legislature shall provide for control of pollution and control of despoilment of the air, water and other natural resources of this state, consistent with the use and development of these resources for the maximum benefit of the people.'
I'm not a water rights lawyer. Florida water law is very different from New Mexico. I do not know if the NM legislature has passed laws allowing cities to pass stricter pollution laws.