Water law in the United States

Water law in the United States refers to the Water resources law laws regulating water as a resource in the United States. Beyond issues common to all jurisdictions attempting to regulate water's uses, water law in the United States must contend with:

The law governing these topics derives from all layers of US law. Some derives from common law principles which have developed over centuries, and which evolve as the nature of disputes presented to courts change. For example, the judicial approach to landowner rights to divert surface waters has changed significantly in the last century as public attitudes about land and water have evolved. Some derives from state statutory law. Some derives from the original public grants of land to the states and from the documents of their origination. Some derives from state, federal, and local regulation of waters through zoning, public health, and other regulation. (Federally recognized tribes may have water rights, but non-federally recognized Indian tribes generally do not.)

The United States inherited the British common law system which develops legal principles through judicial decisions made in the context of disputes between parties. Statutory and constitutional law forms the framework within which these disputes are resolved, to some extent, but decisional law developed through the resolution of specific disputes is the great engine of water law.

These disputes arise in a number of contexts. When the state, local, or federal government takes private property that has water rights associated with private ownership, the value of that property is significantly affected by its water rights. And, properties located along public waters are quite common, because of the importance of public waters to commerce, the environment, and recreation. These taking cases represent a major source of the law defining the limits of private rights in water and public rights.

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