Water law is often a matter of competing interests. Historic property rights come into conflict with growing populations, and lawmakers and courts must decide who has the superior claim. As a result, much of state water law is focused on the ownership of various water sources and on how to decide conflicting claims. These laws also govern the quality and allocation of water within state borders.
In addition, water sources often stretch across multiple states. This has resulted in the development of interstate agreements regarding the use of water resources. These agreements are generally concerned with maintaining water quality and ensuring water availability for all of the water resource's users.
This guide provides links to foundational resources on state water laws, with a focus on interstate agreements and on three of the major water-using states: California, Colorado and Texas.