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Study Concludes Colorado River Reservoirs Could Bottom Out from Warming, Water Management Business-as-Usual

Colorado River Basin including major dams. Inset (a) shows water demand and losses and supply. Pink: 9-year moving average of the natural flow above Imperial Dam, AZ. Blue: 9-year moving average of the total consumptive use in the Lower and Upper basin. Inset (b) shows 5-year moving average of paleo reconstructed flows at Lees Ferry, AZ. The red line is the natural flow from the observational period. Source: AGU. Click to enlarge.

All reservoirs along the Colorado River might dry up by mid-century as the West warms, according to a new study led by researchers at the University of Colorado, Boulder. The probability of such a severe shortage by then runs as high as one-in-two, unless current water-management practices change, the researchers report in a paper to be published in the American Geophysical Union (AGU) journal Water Resources Research.

The study’s coauthors looked at the effects of a range of reductions in Colorado River stream flow on future reservoir levels and at the implications of different management strategies. Even under the harshest drying caused by climate change, the large storage capacity of reservoirs on the Colorado might help sustain water supply for a few decades. However, new water management approaches are critical to minimize the chances of fully depleting reservoir storage by mid-century.

This study, along with others that predict future flow reductions in the Colorado River Basin, suggests that water managers should begin to re-think current water management practices during the next few years, before the more serious effects of climate change appear.

—Balaji Rajagopalan, lead author

Water supply from the massive reservoirs on the Colorado River (currently about 60 Million Acre Feet (MaF) or roughly four times the annual average flow in the river) has historically rendered the water supply reliable even when taxed by severe drought such as the early 1990s. This capacity, the researchers note, has been the backstop supporting population growth and economic expansion in the southwest United States. Roughly 30 million people now depend on the Colorado River for drinking and irrigation water.

The annual basin deliveries have risen in recent decades and now approach the annual average river flow. With the projection for further demand increase, the reliability of the water supply becomes increasingly dependent on reservoir storage.

—Rajagopalan et al.

The Colorado River system is enduring its tenth year of a drought. The river system entered the drought in 2000 with the reservoirs at approximately 95% of capacity. The reservoir system is currently at 59% of capacity, about the same as this time last year, says Rajagopalan.

The research team examined the future vulnerability of the system to water supply variability coupled with projected changes in water demand. They found that through 2026, the risk of fully depleting reservoir storage in any given year remains below 10% under any scenario of climate fluctuation or management alternative. During this period, the reservoir storage could even recover from its current low level, according to the researchers.

But if climate change results in a 10% reduction in the Colorado River’s average stream flow as some recent studies predict, the chances of fully depleting reservoir storage will exceed 25% percent by 2057, according to the study. If climate change results in a 20% flow reduction, the chances of fully depleting reservoir storage will exceed one in two by 2057, Rajagopalan says.

On average, drying caused by climate change would increase the risk of fully depleting reservoir storage by nearly ten times more than the risk we expect from population pressures alone. By mid-century this risk translates into a 50 percent chance in any given year of empty reservoirs, an enormous risk and huge water management challenge.

—Balaji Rajagopalan

Implementing more aggressive management practices—in which downstream releases are reduced during periods of reservoir shortages—could lead to only a two-fold increase in risk of depleting all reservoir storage during this period, according to the study.

The magnitude of the risk will ultimately depend on the extent of climate drying and on the types of water management and conservation strategies established.

The study was conducted with support from the Western Water Assessment, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration (NOAA), as well as CADSWES and the Bureau of Reclamation.

Other study authors included James Prairie of the Bureau of Reclamation, Martin Hoerling and Andrea Ray of NOAA, Joseph Barsugli and Bradley Udall of the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU-Boulder, and Benjamin Harding of AMEC Earth & Environmental Inc. of Boulder.


  • Balaji Rajagopalan et al., Water Supply Risk on the Colorado River: Can Management Mitigate? Water Resources Research, in press.



This is what already happened to many natural fresh water reservoirs in Russia over the last 50 years.

Water mismanagement is often one of the main reason.

The same thing could eventually happen to the Great Lakes if we keep over-using the water for farming, industrial, domestic and other purposes.

Effective water conservation may become a neccessity, specially if agriculture is used on a wide scale to produce alternative fuels.


Luckily Global Warming is just a Liberal Conspiracy, so don't worry. The Invisible Hand™ of the Free Market System will find a way to fill the Colorado River with water.


The Dept of the Interior really needs to be working with the Canadian government to buy Canadian water. I believe that since they are downstream the US needs to do so, even if the diversion is from American rivers, i.e. the Flathead River being diverted under the continental divide to the Sun River and then into the Missouri, or the Blackfoot River being diverted into the Missouri via Wolf Creek. The only question is, how expensive is it to build a small feeder dam at say 6000' on the Flathead side (west side of the continental divide), drill a nearly horizontal pipeline just below it to the Missouri side with about 1' of drop every 20'. It would need to be at least a mile in length to allow the water build up to be worth drilling for. 3 or 4 small pipes would allow the down stream effect to be spread over several rivers, rather than depleting/augmenting one to excess.
I realize that the diversion would probably be too expensive with water prices per acre foot in the past, but in the future the cost of water may make a similar scheme workable. Fort Peck reservoir is off its historic low, but it really needs more water from upstream, or the Corps has to slow the flow past the dam.


So stop pulling water from the reservoirs - start building pipelines from the Ogallala Aquifer, with water supplied from wells installed in areas where there is no possibility agriculture...kind of like what T. Boone Pickens wants to do to supply the Dallas area with water.... http://www.mesawater.com/ogallala.asp


Most of the Colorado river water going to California was and is used for agriculture. Arizona asserted their rights to the water and built golf courses and tall water fountains. Water management IS required for sure, fresh water is a precious resource.


ejj, I am not sure if you are joking, if so, it is kind of funny. But, if you aren't joking, drawing any more water out of the Ogallala Acquifer is a horrible idea! The water level is dropping like a rock as it is, that is why drawing from the over supply of water that flows through Canada is so important. The two main draws on the Missouri's reservoirs are both important, i.e. electricity generation and, less critical but still important in the Corps eyes, maintaining a river level adequate to maintain barge traffic up as far as Lake Saccaccawea (sp?). One of the secondary uses of the water that would have ended up flowing through Canada to the Pacific would be to reduce the draws from the Ogallala to allow it to recover.


Water resources in the west have been the big issue ever since settlers moved west. The Ogallala Aquifer has and is being overdrawn for farming.

Agriculture takes more than 80% of the water in California and that includes use by more than 30 million people.

Many of the farm acres depend on predictable rainfall in the plains states, irrigation is too expensive, even IF they had a huge water resource, which they do not.

Fresh water resources are a national issue. Some states get more rainfall than others and that is where water distribution comes in.


Has anybody looked at the USA per capita total fresh water consumption for the last 100 years?

At the same rising rate, fresh water could quickly become a rather rare and expensive commodity.

Canada being blessed with abondant supplies could become a very rich nation exporting clean fresh water to very heavy consumers south of the border. Something like a mere $0.10/gal as a starting price, going up with inflation at the rate of 2% to 3% per year would do. Multiplied by trillions of gal. per year.... the daily revenues could be very interesting.

In no time, Canada could raise the incentives to $25K to buy PHEVs and BEVs (to reduce consumption of fuel and curtail tar sand oil extraction activities, stop production of grain ethanol, (to liberate more fresh water for sale) reduce income taxes etc.

Great future for Canada.


This is what aggrivates me so much about proponents of hydrogen cars. They all say that it is made from a limitless resource (water). I read a article in popular mechanics a while back that said that the earth already consumes 75% of the avalible fresh water.

After oil is gone the next wars will be fought over water rights.



80% of the water goes to agriculture, but there must be some room for optimization in that 80%. Some crops (rice comes to mind)are monsoon crops that really shouldn't be grown in Southern California. The simple answer is probably just to raise prices for water drawn from the Colorado River. Many of the resevoirs on the West Coast are low right now from a couple dry years, and water really ought to be rationed pretty far and wide.


Brian there is a huge difference between the water needed for generating h2 and the water needed to drink or water plants.


They grow rice in the Sacramento Davis area because of the huge amount of snow pack run off from the Sierras. The old levy system can not handle the surge, so they flood rice fields. Once they get the levies upgraded, this may not be the case, but for now it works.


Okay build a massive desalination plant near New Orleans powered by a new nuclear power plant. Build a pipeline (like Alaska pipeline) to the Ogallala & pump water into the aquifer for storage and use. Pump the "concentrated seawater" from the desal process into the Mississippi delta deadzone...it's already dead and isn't coming back anytime soon. The goal is to minimize evapotranspiration. Simple (though not easy) solutions.



I think you are not serious in your proposals, Ogallala aquifer is fossil water and does not replenish, its level has gone down by 150 feet since they started to pump it, it will run dry within 50 years from now.

Desalinisation is costly and requires huge amount of energy, it won't be used for agriculture, only for table water at best.

The only solution is to stop growing thirsty crops like corn, rice and coton in California, only crop that can thrive in dry climate, fruit and vegetable ok, but only using dripping systems, foils on the soil to prevent loss by evaporation.

but pointing at agriculture is not enouh, we need to recycle water (like they do in israel) and ban lawn which is an irresponsible waste of water.

California spend 10% of its energy just to push water. think of it


To desalinate seawater (by inverse-osmosis), you need a pressure of 30 bar. Actual desalination plants are close to this theoretical optimum. So, the amount of energy needed to desalinate seawater is equal to pumping it 300 meters upwards. So you need about 3MJ to desalinate 1000 litres of water. One nuclear plant of 3GW can thus idealy produce 1000 tons of water per second. In practice it will be somewhat less, but still enough.

That is, of course, if you use electricity to desalinate. If you use the electricity to drive your cars, and use the waste-heat to desalinate, it's even more efficient.

As an alternative, thermal solar plants using seawater have an enormous co-production of fresh water...

The Goracle


Earth has been cooling for the past ten, plus, years but warming causes this "problem." FANTASTIC NEWS!... Since Earth is not warming (the claimed cause of the "problem") the "problem" has already reversed itself! Woo, hoo!!!

Thank you, politicians, for doing something about Global Warming® after is has been found to be false. Please adjust all of our history accounts (with the force of law and jail) to show that you did something about Global Warming® BEFORE it reversed, thereby allowing you to lay claim to correcting the Global Warming® issue.


Will S

Goracle wrote;

"Earth has been cooling for the past ten, plus, years"

Then how do you explain this past June as being the second warmest on record, second only to 2005?

NCDC: Climate of 2009

"Based on preliminary data, the globally averaged combined land and sea surface temperature was the second warmest on record for June and the January-June year-to-date tied with 2004 as the fifth warmest on record."

"El Niño–Southern Oscillation (ENSO) transitioned from ENSO-neutral to El Niño conditions across the equatorial Pacific Ocean during June 2009. If El Niño conditions continue to mature as projected by NOAA, global temperatures are likely to continue to threaten previous record highs."


Solar thermal plants located near the ocean can generate power and provide fresh water. Each acre can provide 1000s of homes with both water and power which saves the fresh water resources for agriculture. We may need to start using drip irrigation in the west. It is more costly, but running out of water for growing melons, tomatoes and lettuce in the Imperial Valley is worse.

drawing from the over supply of water that flows through Canada is so important.
It's nice how Canada is viewed as a 51st state with no autonomy to make its own decisions. We have our own water problems.

Our country's population is growing fast too and so is our water demand. Yes, doing things to make agriculture more efficient is nice, but still, the economic system in North America is rotten to the core and until it is fixed the problem won't go away -- it will only get bigger.

Until we get out of the flawed economic system that relies on eternal population growth then we are going to have both increasing water demand and decreasing natural lands to supply the human population, end of story.

There are several major structural problems in the North American economy, the most significant being the loss of its manufacturing base to overseas outsourcing. This, along with mechanized industrial farming, has resulted in a lot of unemployment that has had to be absorbed into the economy by growing it bigger every year. The economy of the US is becoming service- and growth- based. It's bigger than before but imbalanced. There's only so many service industry jobs to provide for the unemployed manufacturing workers so the rest of the unemployed workforce has been devoted to building new houses and the infrastructure to support them, a continuation of the mania of new suburb development used as a make work project after WWII -- that's what keeps the US economy going -- simply growth to absorb all the newcomers. The whole economy is centered around this.

We are like this in Canada too but at least we have natural resources to offset our trade deficits and provide some base for the economy. You got major problems in the US, you need to fix your economy at a fundamental level rather than once again, simply looking to other countries to take resources from to satisfy your growing inefficient and insatiable appetites.


Rather than looking to Canada for your water needs why don't you do something about the flooding of the Red River of the North. This river starts in the US, flows northward through the Red River Valley and forms the border between the U.S. states of Minnesota and North Dakota before continuing into Manitoba, Canada. It empties into Lake Winnipeg, whose waters join the world's oceans in Hudson Bay via the Nelson River.

If you could dam it before it crosses the border and send the winter flood waters elsewhwere that would go a long way to solving both our water problems. Of course seeing as how the Red River actually flows across the flat lakebed of the ancient glacial Lake Agassiz, an enormous glacial lake created at the end of the Wisconsin glaciation from meltwaters of the Laurentide ice sheet, the damming of it might be a tad "difficult."



If we use coastal solar thermal power plants to distill water, what happens to the salt and other solids in the sea water? Wouldn't they foul or corrode the system?


The brine could be 'dumped' back in the ocean (at a safe place where enough current dissipates it again) or used as a resource. At the moment, massive amounts of salts are used in industry for production of NaOH, Cl2, PVC, NaOCl, ... .
Actually, this salt-industry is also unsustainable and environmentally unfriendly, since we use geological salt depositions. Eventually this salt ends up into the oceans, making it ever more salty, mining harms the environment, and we will run out of it some day. It would be better to use oceanic salts anyway. Next, the iodium and Magnesium in the brine could be a valuable resource today. (a lot of the actual Mg used in the world is produced from brine) Anyway, in many places seawater is being evaporated in large 'lakes' for the production of natural seasalt. If you could start with a brine that is 10 times more concentrated, it would enhance production significantly.


The solar thermal plant is indirect. You run a thermal oil through the collectors that runs through a heat exchanger made of stainless steel. What you do with the brine left over is up to you, bury it, flush it back to the sea or harvest it for minerals.


Sending salt to the ocean is not a problem as long as it is dispersed. Super salination happens in lots of places around the world like in Mexico where you get salt flats. The oceans aren't going to get too salty. When I was a kid I was worried about this, but then I learned that once the ocean becomes too salty it precipitates out at depth and maintains a balance.


the pressure to reverse osmosis is more like 200 bars rather than 30 bars, the minimal energy you need is 2kWhrs/m3. If you use evaporation/condensation you need much more than this, But again Desalinisation won't be used for agriculture even using solar energy, it is way way too costly. Nobody with some background in the area even think about it. When the Ogalalla aquifer will get depleted the food production in US will drop by a mere 20%.

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