structural:reformatting, linguistic:paraphrasing, structural:scholar_edition
Origin

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 appropriation doctrine originated in Gold-Rush – era California, when miners sought to acquire water for mining operations. In the 1855 case of Irwin v. Phillips, Matthew Irwin diverted a stream for his mining operation. Shortly afterward, Robert Phillips started a mining operation downstream and eventually tried to divert the water back to its original streambed. The case was taken to the California Supreme Court, which ruled for Irwin.