The San Juan drainage delivers water consistently due to its immense snowpack and geographic location high in the Rocky Mountains. San Juan/Chama Project water flows from three rivers in the Colorado River basin (Rio Blanco, Navajo River, and Little Navajo River) through tunnels and aqueducts into the Chama River to be stored in the Heron, Abiquiu, and Cochiti reservoirs before it is used in Santa Fe and Albuquerque, offsetting aquifer drawdown.

The approximate 100,000 acre-feet per year (AFY) of water that flows through the project is counted separately from Rio Grande water for compact and treaty purposes. (An acre-foot is water one foot deep that covers one acre. It is enough water to service two average households per year.) If the San Juan/Chama water delivery is low, some farms and riparian areas important for endangered species in the Rio Grande basin will wither, although significant amounts of water may still flow by on its way to Mexico or Texas. This is exacerbated in areas where channels have diverted the flow of the river from its original riverbed.

Otowi Gauge is the measurement point along the Rio Grande that determines the yearly water volume that will be delivered to Texas at Elephant Butte. Water that flows from Elephant Butte to the border of Texas is used by farmers and municipalities along the way. This area is called Compact Texas and is subject to the lawsuits between the states and the effects of drought.

The Albuquerque Water Treatment Plant is one of the major tributaries to the Rio Grande. It provides roughly 50,000 AFY of water to the river, cleaning it in order to meet the stringent specifications of the downstream Isleta Pueblo. The water is considered a reintroduction of San Juan/Chama water back into the river after the City of Albuquerque has used it.

Once the river reaches El Paso, a mean streamflow of 640 cubic feet per second (CFS) is largely determined by releases from Elephant Butte Reservoir. Three diversion dams move water across state and national lines to complete the operations of the Rio Grande Compact.


This article is part of “Water Scarcity: Elephant Butte Reservoir,” written solely by Kathleen Kambic, assistant professor at the University of New Mexico. All images are her work alone, unless noted otherwise in the text.

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The views expressed here are those of the authors only and do not reflect the position of The Architectural League of New York.