Conceptual Restoration Plan Update: Phase I
WATER AVAILABILITY TRENDS
Rio Grande Compact
In 1938, after years of negotiation, the states of Colorado, New Mexico, and Texas agreed to the Rio Grande Compact (Compact). The Compact is one of the legal cornerstones governing operation of the Rio Grande and its reservoirs above Caballo Dam. It apportions the river water among the three states according to a specified annual delivery schedule that depends on the flow at designated index stations. The Compact is administered by a commission that has a delegate from each state and a nonvoting federal representative.
The Rio Grande Compact apportions the waters of the Rio Grande north of Fort Quitman, Texas, between the states of Colorado, New Mexico, and Texas. This division of the total drainage basin of the Rio Grande was adopted by the Treaty of 1906 between the United States and Mexico and has been used consistently since that time. The adoption of the Compact represented the culmination of a lengthy and sometimes contentious debate among the three states and the federal government over the water resources of the basin.
Middle Rio Grande Water Management
Operation of the Middle Rio Grande in the Project Area is guided by these regulations as well as agency authorities and requirements. Upstream water storage facilities include Cochiti Reservoir on the mainstem of the Rio Grande, Heron, El Vado and Abiquiu Reservoirs in the Rio Chama Watershed, and other smaller dams situated on Rio Grande tributaries. These facilities store snowmelt runoff water to meet industrial, municipal, and agricultural needs in the Middle Rio Grande, and provide flood protection, sediment retention and recreation. All of these effect delivery of Rio Grande flows to the project area.
In the last 15 years, water and land managers, regulatory agencies and interested groups have worked together to develop management strategies that allow for flexible water management for multiple goals. The source of Rio Grande flows entering the project reach is a combination of flows coming down the main stem of the Rio Grande from Colorado, inputs from the Rio Chama and contributions from numerous other New Mexico tributaries and Colorado.
The winter snowpack in the watersheds of the Upper Rio Grande determines the magnitude of flows in the Rio Grande through the Project Area that year, with average and above average snowpack typically delivering spring runoff flows large enough to exceed the channel capacity resulting in floodplain inundation and channel reworking. In years with below average snowpack there typically are no high spring runoff flows and water management becomes critical as the limited supply is managed to supply irrigation demands while trying to maintain flow in the river or at least control how the river dries to cause the least damage to wildlife.
Middle Rio Grande Conservancy District (MRGCD) irrigation diversions are from March 1st through October with limited irrigation for the Pueblos continuing through November. There are three irrigation diversion dams in the Middle Rio Grande; Angostura, Isleta, and San Acacia which is within the Project reach. Currently San Acacia is rarely used to divert irrigation water, instead irrigation water for the area historically supplied by San Acacia diversions is diverted farther upstream at Isleta and transported to the San Acacia headworks through MRGCD ditches. This decreases flow in the Rio Grande between Isleta and San Acacia during irrigation season. Another diversion in the Middle Rio Grande is for the Albuquerque Bernalillo County Water Utility Authority which diverts water for municipal use at Albuquerque.
MRGCD has implemented a Conservation Program over the past 15 years to manage outfall delivery, generate sources of water to be used for habitat restoration, and improve efficiencies. The Program is a comprehensive effort to increase MRGCD 'resilience to variable water supply, and to address new challenges faced by water users.’ MRGCD is also working to implement projects with private landowners.
Some examples of Rio Grande water users working together to increase the beneficial use of Rio Grande water include short term storage of water in Cochiti Reservoir which is released at a higher flow to generate a spawning pulse for the Rio Grande silvery minnow (Hybognathus amarus) during dry years, and stopping irrigation diversions for several days, again to generate a spawning pulse but also moving water down the Rio Chama at higher flows on summer weekends to benefit rafting. Reclamation works with water users to purchase water for supplemental flows to limit river drying in dry years. Audubon also has a water leasing program that can be found here.