Spray irrigation on a field in the Imperial Valley in southern California. This type of irrigation is a lot better than the extremely water inefficient type of flood irrigation that is popular in this region. Still, in the high temperatures of this desert region a lot of the water evaporates, leaving the salts, that are dissolved in the colorado River water that is used, on the soil.

Colorado River Delta

A map of the Aqueduct route from the Colorado River to the Coastal Plain of Southern California and the thirteen cities via the Metropolitan Water District of Southern California.

Why we need the water – pro-Colorado River Aqueduct bond map from the Metropolitan Water District of Southern California.

How much water reaches the Westwater stretch of the Colorado River, and then Lake Powell, is taking on increasing importance to Colorado water officials. A new study is underway to look at much more water is available to develop on the Western Slope, and it’s caught the attention of east slope water officials. Photo: Brent Gardner-Smith/Aspen Journalism

The Colorado River supplies water to Lake Mead, the largest man-made reservoir in terms of capacity in the United States. New research from The University of Texas at Austin has found natural variability, not humans, have the most impact on water stored in the river and the sources that feed it. U.S. Geological Survey

Colorado River Basin, USBR May 2015

Herbert Hoover presides over the signing of the Colorado River Compact in November 1922. Members of the Colorado River Commission stood together at the signing of the Colorado River Compact on November 24, 1922. The signing took place at the Palace of the Governors in Santa Fe, New Mexico, with Secretary of Commerce Herbert Hoover presiding (seated). (Courtesy U.S. Department of Interior, Bureau of Reclamation)

Young girl enjoying the river restored temporarily by the pulse flow March 2014 via National Geographic

Colorado River pulse flow (Minute 319) reaches the Sea of Cortez for the first time since 1998 on May 15, 2014 via the Sonoran Institute

Hayfield message to President Obama 2011 via Protect the Flows

From The San Francisco Chronicle (David Wiegand):

Water is politics — you’ll hear that phrase used in the often-fascinating Discovery Channel documentary “Killing the Colorado,” airing Thursday, Aug. 4.

The film teams five award-winning directors to explore what happens when people alter the course of waterways such as the Colorado River. The impact of diverting, damming or otherwise interfering with how water flows can be felt far beyond the area immediately around the water. And in many cases, it has led to environmental fatalities…

California fostered the growth of its major metropolitan areas by taking more than its fair share of water from the Colorado River, whose watershed extends minimally into the state, but enough to make it perhaps too readily available…

As water has become scarce, the demand for it has increased along with the population. That’s simple math, but deciding who gets water and how they’ll get it is anything but simple. Water has become so valuable that several interview subjects declare that water is to the current century what oil was to the last.

In fact, the soaring value of water has sparked the rise of several companies that buy and sell water as they do with other commodities such as gold and pork bellies. Firms such as Water Asset Management have made the water business a billion-dollar industry.

The film is kind of a patchwork of chapters overseen by different directors, including Rob Epstein and Jeffrey Friedman (“Common Threads: Stories From the Quilt”), Barbara Kopple (“Harlan County: USA”), Jesse Moss (“The Overnighters”) and Alan and Susan Raymond (“Doing Time: Life Inside the Big House”).

“Killing the Colorado” is based on an investigation of water issues published through ProPublica by Abrahm Lustgarten, who appears with useful insight and commentary at various points in the film.

The film offers a detailed example of the implications of water diversion when it looks at a proposed project for the Gila River in Arizona. The river is the subject of a squabble between Arizona and New Mexico, which wants to use a greater share of the water. A diversion plan is in the works, but given how precious water is, especially in the American Southwest, opponents haven’t given up trying to block it…

The plan is going to be costly but will only benefit a relatively small number of people. At least that’s what folks on the Arizona side of the border argue.

We also see what happens when a community with water tries to make a buck off of it. In the case of Crowley, Colo., a lot of bucks. The town sold so much of its water that it decimated its own economy and went from being one of the state’s better-off areas to one of its most impoverished…

Farmers have always been either victims or scapegoats in water issues. They are often blamed for water shortages because they are by far the dominant consumers of water in this country. Yet, to get an idea of how little clout farmers have with regard to water decisions, just drive along Interstate 5 in California, especially as it cuts through the Central Valley. You’ll be greeted by signs along the road expressing outrage at Congress for leaving farmland high and dangerously dry.

Alfalfa, for example, is one of the best ways of feeding cattle. If farmers can’t grow alfalfa, it affects dairy farming and the beef cattle industry. Yet they are targeted for growing a plant that needs a lot of water to thrive.

However, if we think of water as a regional problem for the West, we’re missing an important point. Much of the food Americans consume is grown in California, which is slowly emerging from a drought. The Imperial Valley, in the southeastern part of the state, is part of the Colorado watershed. If someone in New York complains about the cost of a fresh kale salad, they can direct their irritation at the scarcity of water in the West.

“Killing the Colorado” is very good. It isn’t comprehensive, though, and parts of it are so clogged with arcane information, it’s sometimes hard to follow. Or swallow, as it were.

Nonetheless, the film is an eye-opener, even for those who think they already know how serious the country’s water problems are.