Rio Grande 101

Today more than ever, as the region warms – and both our surface and groundwater supplies become increasingly constrained – it’s a good time to check the facts and try to understand one another. In that spirit, here’s my crack at a “FAQ” about New Mexico’s beloved Rio Grande.

Who gets the water?

The Rio Grande flows almost 1,900 miles from Colorado to the Gulf of Mexico, passing through three states and two countries and providing water to millions of people. Its waters pour onto alfalfa and chile fields, pecan orchards, and lawns. The river supplies drinking water for cities like Santa Fe, Albuquerque, Las Cruces, El Paso, and Ciudad Juárez. Its waters are diverted onto golf courses, like Santa Fe’s Las Companas. Even factories like Rio Rancho’s Intel rely on the river: they must buy water rights from farmers to offset the effect their groundwater pumping has on the river.

Signed in 1939, the Rio Grande Compact divvies up a significant portion of the river’s water among Colorado, New Mexico, and Texas. The amount of water states can keep each year isn’t based on a set number. Rather, it has to do with how much water is actually in the river that year.

As staffers at the New Mexico Interstate Stream Commission explained to me last year, Colorado’s water delivered to New Mexico is based on the Lobatos stream gage on the Rio Grande near the state line. Then, New Mexico delivers Texas’s water based on the sum of the measured flow below Elephant Butte dam for the year and the change in storage within the reservoir.

Colorado cannot hoard water, and Texas isn’t stealing it from us. There’s even a case before the US Supreme Court in which Texas claims that by pumping groundwater that’s connected to the river, New Mexico is taking water that’s legally supposed to flow to Texas.

How is water divvied up in New Mexico?

Water in streams and rivers belongs to the public. It’s held in trust by the state, which grants water rights (private property rights, basically) to farmers, cities or businesses. The system was set up in the early 20th century, even before statehood.

Unlike some states, New Mexico doesn’t grant what are called “instream water rights” to its rivers. That means the Rio Grande itself has no rights to its water.

Farmers typically hold older, more senior water rights; cities usually have junior rights. The pueblos in the Middle Rio Grande have the oldest and most senior water rights—and the amount of water they actually “own” has never been quantified. That, however, shouldn’t lead people to believe that tribes are taking all the water.

How is most of the river water used in New Mexico?

Most of the river’s water is used for agriculture.

Here in the Middle Rio Grande, 70 percent of the water used comes from the river. More than 60 percent of all the water goes toward agriculture. In southern New Mexico, 60 percent of all water used comes from the river—and 87 percent of the total is used by agriculture.

Read the rest of the article on New Mexico in Depth. And check out the whole New Mexico Changing Climate Project.

Featured image from Laura Paskus, New Mexico in Depth

Rio Grande 101