Colorado River

 InvestigateWest takes note of two recent reports from the global warming frontlines in the West. At a forum this week in Aspen, the general manager of the Colorado River Water Conservation District said a lack of informed consensus about global climate change make it difficult to manage future water research, according to a report in the Colorado Independent. In other words, despite no lack of evidence that the West is facing dramatic water shortages due to global climate change, the management piece isn't happening, mainly because of public doubts. Solid evidence by the Colorado Water Conservation Board and other reports show that a shrinking snow pack and earlier spring runoff mean far less water in the Colorado River, yet half of Colorado residents doubt the facts.

In other states, it's even worse, said Dr. Eric Kuhn, pointing to a study done by the Rocky Mountain Climate Change Organization.

In Wyoming, the survey found only 35 percent of people think climate change is a reality, while 62 percent of Californians think so, and 74 percent of Democrats surveyed in a seven-state area think it's a reality, compared to just 25 percent of Republicans.

Meanwhile, the Idaho Statesman's Rocky Barker writes of gardeners and outdoor enthusiasts dealing with the impacts of climate change. Gardeners talk about temperatures warming to the point where hardy bananas could actually be grown in Idaho's "banana belt," and hunters, fishers, campers, boaters and hikers coping with forest fires that have increased 400 percent since 1980. The warmer winters mean less snow for skiers.

Our reporting trip to the Salton Sea is over, and we're headed back over the mountains to LA catch a plane. I'd love to stay a few more days, because it's turning out that the Salton Sea is a man-bites-dog story in another sense from the one I cited yesterday.

Here's why: After years of hearing about how the agriculture that surrounds this key stop on the Pacific Flyway is harming the sea, it now turns out that ag and the Sea's defenders are making common cause.

That's because what the farmers need is water. And what the Sea needs is water. And they're both going to lose it.

As part of a massive reordering of the way water is used in Southern California, something like 2oo,000 acre-feet of water a year -- that's roughly 100,000 Olympic-sized swimming pools -- will be withdrawn from use by farmers whose Imperial Valley fields surround the Sea.

Now, you need to understand that water flows into the sea, but not out. Something like six feet of water evaporates every year. And why is it a "sea" if it's inland? Because the Colorado River water that's diverted into the farm fields around here carries with it a small amount of salt, along with pesticides, fertilizer and selenium. Over the years, water dumped on the farm fields flowed eventually into the sea, carrying its light load of salt. But as the water evaporated, it left behind a larger and larger load of salt. (Update/clarification 9/12/09: I realize in re-reading this that it might not be clear that a lot of the salt ending up in the sea is actually leached from the farm fields immediately surrounding it. I guess I also should have mentioned that the Salton Sea already is saltier than seawater.)

So long as water continues to flow into the sea, and continues to evaporate, the water gets saltier and saltier.

Rural Arizona is searching for a stable source of water. The existing patchwork system of wells and reservoirs is wearing thin, Shaun McKinnon writes in the Arizona Republic. Flagstaff water-resources Chief Brad Hill told the Republic that the rural parts of the state need to plug into the Colorado River. But competition for that water is also fierce. In the meantime, rural communities wrestle with how best to balance growth with water needs.  In urban centers, new developments must verify they come packaged with a 100-year water supply before they are allowed to be built. Rural towns have no such restrictions.

There's been as steady drain on underground water reserves in the state, McKinnon writes in an earlier extensive story. Excessive reliance on groundwater supplies could prove "potentially disastrous," resulting in wells running dry and aquifers collapsing. Such failures could alter the landscape itself, creating fissures and sinkholes. Drought and climate change are also straining surface-water supplies at the same time that groundwater resources are shrinking. Herb Guenther of the Arizona Department of Water Resources told McKinnon: "What we have to do is get out of denial."

[caption id="attachment_1528" align="alignright" width="200" caption=""Lake" Powell, one of the big Colorado River reservoirs threatened by climate change. Photo courtesy University of Colorado."][/caption]

Climate refugees. There it is again, this notion that large-scale migrations caused by climate change could be in the offing.

When we wrote about this a few months ago based on a climate conference in Seattle, the story got a lot of attention. Today this climate-refugees idea came up again in a story by Bruce Finley of the Denver Post on a new study of climate change's possible effects on the Colorado River.

The study (sorry -- no link; it's not posted to the Web yet) says there's up to a 50-50 chance of seeing Colorado River reservoirs run dry by mid-century, given current management practices, increased demand and the expected drying effects of climate change.

Now, that last one's not something that's easy to quantify in a projection. But lead author Balaji Rajagopalan of the University of Colorado and other researchers simply took a look at what would happen if water in the Colorado River system were reduced 10 percent or 20 percent due to hotter temperatures (which would increase what the water wonks call evapotranspiration, a combination of evaporation and plants' transpiring of water.)

Well, guess what? By mid-century there's about a 50-50 chance of the Colorado River's two major reservoirs, Lake Powell and Lake Mead, will run dry. That's under the 20 percent reduction scenario.

Global warming could deplete the Colorado River system's reservoirs by the middle of this century, according to the Associated Press. A study by University of Colorado researchers says warming trends could cut the river's average flow by 10 percent, and drain the reservoirs by 2057. The reservoirs along the river supply drinking and irrigation water to 39 million people.

More on this at our Dateline Earth blog: http://bit.ly/19WJOp .