Colorado Water 2012: ‘The Rio Grande starts as a small spring’ — Steve Vandiver

Map of the Rio Grande watershed. Graphic credit: WikiMedia

Here’s the latest installment of the Valley Courier’s Colorado Water 2012 series. Here’s an excerpt:

The Rio Grande starts as a small spring and as it proceeds downstream it picks up a number of small tributaries and soon is a large stream and then a small river as it flows into the only main stem reservoir on the river in Colorado, Rio Grande Reservoir. This is a private reservoir which is used for irrigation and other uses.

The river then runs downstream and joins the South Fork of the Rio Grande and then towards to the San Luis Valley. On its way through the Valley, there are a number of diversions into irrigation ditches which divert the allocation of the Compact dedicated to Colorado. There are limits to how much Colorado can use and the remainder has to go on downstream to New Mexico which creates a portion of their water supply under their allocation from the Compact.

After running through the Rio Grande Gorge for a number of miles and joining a number of small tributaries in northern New Mexico, it runs into a large flood control reservoir above Cochiti Dam. The largest tributary to the river in New Mexico is the Chama River which enters the river just below that dam, delivers about one-third of the supplies for New Mexico. New Mexico then uses their allocation of Compact water for agriculture and municipal supplies through the central portion of the state. The cities of Santa Fe, Albuquerque, Socorro and others rely on the river as a source of supply.

The river then enters the largest reservoir on the Rio Grande in the Upper Rio Grande reach, the Elephant Butte dam and Reservoir. This reservoir is critical to the entire Rio Grande Basin as it holds and regulates southern New Mexico and West Texas allocation under of the Compact, generates hydroelectric power and provides protection for all three states’ water supplies.

Immediately below the Elephant Butte dam is Cabello Reservoir which serves as a regulating reservoir from the water running through the power generation station in Elephant Butte Dam. There are three large diversions from the River between Cabello Dam and El Paso that provide irrigation water to several tens of thousands of acres of highly productive land. El Paso uses a portion of Texas’s water allocation for municipal supplies. The American Dam diversion just upstream of El Paso serves many thousands of irrigated acres downstream of El Paso before the river gets to Ft. Quitman. The water allocated from the river to the Juarez, Mexico area by treaty with the US, is diverted at the International Dam just below the American Dam. The river is effectively dry below this point except for the water produced by several drains from both the US and Mexico sides of the river.

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