Treaty of Guadalupe Hidalgo The Treaty of Guadalupe Hidalgo of 1848 is a peace agreement that ended the Mexican-American War and is the earliest compact of any kind that dealt with water rights in New Mexico. Under the agreement, the United States received land that now make up California, Nevada, Arizona, Utah, New Mexico, Colorado, Wyoming, and Texas. Mexicans who inhabited these areas were given the option to receive American citizenship and remain on their land. Article VIII of the treaty states that “property of every kind…shall be inviolably respected” which included water rights. Since most of the surface water rights in the Rio Chama Basin were established before 1848, when the treaty was signed, they were protected by the treaty (Rio Chama Regional Water Plan).
Rio Grande Compact The Rio Grande Compact is an interstate water delivery agreement between Colorado, New Mexico, and Texas that was first signed in 1938. The purpose of the Compact is to equitably divide the waters of the Rio Grande basin. The Compact permits Colorado, New Mexico, and Texas to develop and use their own water resources so long as they continue to meet Compact obligations (Langman & Anderholm, 2004, p. 2). Administration of the Compact is overseen by the Rio Grande Compact Commission who meet annually to discuss and adopt an annual report for the previous calendar year. There is also an annual meeting of engineer advisers from various US Federal agencies and the International Boundary and Water Commission who determine the schedule of water deliveries under the Compact. Storage and release of native Rio Chama water is governed by the Compact while San Juan-Chama Project water that is transported by the Chama is not (Langman & Anderholm, 2004, p. 2). Although all San Juan-Chama Project water passes through the Rio Chama on its way to the Rio Grande, this water is not available to irrigators in the Rio Chama Basin.
Vital Infrastructure The three dams on the Rio Chama are key to the water delivery operations mandated by the various agreements. Heron Dam was completed in 1971 by the U.S. Bureau of Reclamation and is used solely for the storage and release of San Juan-Chama Project water (Langman & Anderholm, 2004, p. 2). El Vado Dam, completed in 1935, is operated by the U.S. Bureau of Reclamation whilst the Middle Rio Grande Conservancy District holds the dam's water storage rights. Native Rio Chama water stored at El Vado is governed by the Compact while San Juan-Chama Project water is not and can be released at any time. During irrigation season, up to 100 cfs of native Rio Chama water is released from El Vado for the use of the senior water-rights holders downstream (Langman & Anderholm, 2004, p. 5). Abiquiu Dam was completed in 1963 and is owned and operated by the U.S. Army Corps of Engineers. It serves mainly as a flood and sediment control structure. Native Rio Chama flows are allowed to pass through Abiquiu at a discharge rate up to 1,800 cfs, which is the downstream channel capacity (Langman & Anderholm, 2004, p. 5).
Langman, J.B., & Anderholm, S.K. (2004). Effects of Reservoir Installation, San Juan-Chama Project Water, and Reservoir Operations on Streamflow and Water Quality in the Rio Chama and Rio Grande, Northern and Central New Mexico, 1938-2000. USGS Scientific Investigations Report 2004-5188. Retrieved from https://pubs.usgs.gov/sir/2004/5188/pdf/sir2004-5188.pdf