N.M. Stat. § 72-1-9

A. It is recognized by the state that it promotes the public welfare and the conservation of water within the state for municipalities, counties, school districts, state universities, member-owned community water systems, special water users' associations and public utilities supplying water to municipalities or counties to plan for the reasonable development and use of water resources. The state further recognizes the state engineer's administrative policy of not allowing municipalities, member-owned community water systems, counties and state universities to acquire and hold unused water rights in an amount greater than their reasonable needs within forty years.

B. Municipalities, counties, school districts, state universities, member-owned community water systems, special water users' associations and public utilities supplying water to municipalities or counties shall be allowed a water use planning period not to exceed forty years, and water rights for municipalities, counties, school districts, state universities, member-owned community water systems, special water users' associations and public utilities supplying water to such municipalities or counties shall be based upon a water development plan the implementation of which shall not exceed a forty-year period from the date of the application for an appropriation or a change of place or purpose of use pursuant to a water development plan or for preservation of a municipal, county, school district, member-owned community water system or state university water supply for reasonably projected additional needs within forty years.