Water reallocations are contentious under the best of circumstances. When a basin lacks a comprehensive adjudication of water rights, the levels of legal and economic complexity and controversy intensify. This paper evaluates the Middle Rio Grande, a region of New Mexico that would seem an ideal location for water markets as the need to reallocate water between existing uses is high. Due to the lack of an adjudication, and other complicating factors such as the Endangered Species Act, proposed transfers require a complex evaluation system created by the New Mexico Office of the State Engineer. Even with this evaluation system in place, many questions linger about the validity of transfers and their larger impacts.