The prior appropriation doctrine defines water alloca tion and water rights in the western United States including New Mexico. Due to vari ations between states prior appropriation comes in many flavors, and New Mexico has some unique ones. New Mexico’s version is illus trated by Chapter 5 (G. Emlen Hall), which sets the con text for the evolution of New Mexico’s water law. Chapter 6 ( José Rivera) de scribes one of the unique institutional aspects of Mew Mexico’s sys tem. This chapter examines in detail New Mexico’s water rights sys tem while the next chapter looks at the horizontal and ver tical relationships that create management conflicts. Water rights define the way a right holder can use water and the relationships between the right holder and others who may have rights or be impacted by that use. Water rights also define the relationships that must be con sidered when water is realloc ated. With most of New Mexico’s surface and ground water already alloc ated, the way these relationships are defined is an im port ant part of the realloca tion process. Another im port ant element in defining relationships is the distinction between pub lic and private rights. New Mexico’s consti tu tion states that the water within the state belongs to the “pub lic.” Thus, pub lic rights are the founda tion of New Mexico’s water rights sys tem. Even though the founda tion is pub lic, a sys tem of private rights was estab lished to alloc ate and control water use. This sys tem of use rights (usufructory rights) required the consent of the rel ev ant gov ern ment (Spain, Mexico, territorial or state) to move the right from the pub lic to the private sector. These private rights may be held by indi viduals, in common by acequias, or by local gov ern ments such as irrigation and conservancy districts. However these rights are held, they are prop erty rights protected from unconsti tu tional taking. These private rights are trans ferable under certain circumstances. Since statehood this sys tem of private rights has been based on the doctrine of prior appropriation with a re cog ni tion of valid rights created prior to statehood. Federal and Indian rights are also
im port ant in fully understanding these “relationships” but are discussed in the next chapter. Prior appropriation gives a tem poral pref er ence to the first person to put water to a bene fi cial use. “First in time, first in right” is the core element of the doctrine. Subsequent (junior) rights have pref er ences in order of their estab lishment. Junior rights with more valu able social, envir on mental or eco nomic uses receive no pref er ence over a valid prior right. But, as will be seen below, enforcing tem poral pref er ences is not common in New Mexico. An early tem poral pref er ence does have im port ance, how ever. It can make a water right more valu able when sold because it enhances the right’s “secur ity of delivery.” Other elements of the appropriation doctrine are also im port ant because they set the para meters for how the water can be used and realloc ated. This chapter starts by examining water rights and realloca tion in New Mexico. This is followed by a discussion of the pub lic rights im port ant to the alloca tion and realloca tion pro cesses. The concluding section offers some thoughts on changes for the future.