To be clear, I'm talking specifically about water rights.
The Western rule is typically "prior appropriation", as opposed to "riparian rights" which dominate the Eastern states:
Water is very scarce in the West and so must be allocated sparingly, based on the productivity of its use. The prior appropriation doctrine developed in the Western United States from Spanish (and later Mexican) civil law and differs from the riparian water rights that apply in the rest of the United States.
The Western rule is typically "prior appropriation", as opposed to "riparian rights" which dominate the Eastern states:
Water is very scarce in the West and so must be allocated sparingly, based on the productivity of its use. The prior appropriation doctrine developed in the Western United States from Spanish (and later Mexican) civil law and differs from the riparian water rights that apply in the rest of the United States.
<https://en.wikipedia.org/wiki/Prior-appropriation_water_righ...>
Not relevant to TFA, just a note on law and its varying origins within US jurisdictions.