In areas with plentiful water and few users, such systems are generally not complicated or contentious.
Water rights could also include the physical occupancy of waterways for purposes of travel, commerce and recreational pursuits.
The legal principles and doctrines that form the basis of each type of water rights are not interchangeable and vary according to local and national laws.
'"[6] The 20th century system of prior appropriation water rights is characterized by five principles: Beneficial use is defined[by whom?]
Environmental uses, such as maintaining a body of water and the wildlife that use it, were not initially regarded as beneficial uses in some states but have been accepted in some areas.
Congress has exercised this power in a variety of ways, including the construction of dams, diverting water from a stream and blocking and restricting use of waterways.
[citation needed] The Fifth and Eleventh Amendment to the U.S. Constitution limit the power of state or federal governments to impinge upon any exclusive use of water by prohibiting the enactment of any laws or regulations that amount to a "taking" of private property.
Laws and regulations that deprive a riparian owner of legally cognizable water rights constitute an illegal governmental taking of private property for which just compensation is owed to the water right holder.
[14] In ancient Rome, the law was that people could obtain temporary usufructuary rights for running water.
[15] Under English common law, all tidal waters were held by the Crown and all freshwater streams were included with title to the lands, with full accompanying rights.
In Finland, waterbodies are generally privately owned, but Finland also applies the Roman law principle of aqua profluens (flowing water), according to which the freely flowing water in waterbodies cannot be owned or possessed.