In 2012, Mexico and the United States interpreted a treaty allocating the use of the Colorado River to protect a stressed delta in Mexico by establishing a pilot programme delivering a base flow to the Delta. Minute 319 is a possible first step toward a permanent adaptive management regime for the Delta because it sets three important international water and environmental law precedents. First, it is a de facto implementation of the ecosystem conservation mandates of the United Nations Convention on the Law of the Non-navigational Uses of International Watercourses. Second, Minute 319 is equally recognition of the emerging duty of riparian States to cooperate in the long-term management of shared rivers. Third, although Minute 319 was the product of sovereign-to-sovereign negotiations, it was made possible by nongovernmental organizations (NGOs). It thus illustrates the important role that NGOs can play in the implementation of international environmental and water law.