Unprecedented Cut in Colorado River Flow Ordered, Due to Drought

By: Dr. Jeff Masters , 3:20 PM GMT on August 20, 2013

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For the first time in history, the U.S. government has ordered that flow of Colorado River water from the 50-year-old Glen Canyon Dam be slashed, due to a water crisis brought about by the region's historic 14-year drought. On Friday, the Federal Bureau of Reclamation--a division of the Department of Interior that manages water and electric power in the West--announced that it would cut water released from Lake Powell's Glen Canyon Dam by 750,000 acre-feet in 2014. An acre-foot is the amount of water that will cover an acre of land one foot deep; 750,000 acre-feet is enough water to supply at least 750,000 homes for one year. The flow reduction will leave the Colorado River 9% below the 8.23 million acre feet that is supposed to be supplied downstream to Lake Mead for use in California, Nevada, Arizona and Mexico under the Colorado River Compact of 1922 and later agreements. "This is the worst 14-year drought period in the last hundred years," said Upper Colorado Regional Director Larry Walkoviak in a Bureau of Reclamation press release.

In the winter of 2005, Lake Powell reached its lowest level since filling, an elevation 150' below full pool. Lake levels recovered some in during 2005 - 2011, but the resurgence of severe to extreme drought conditions have provoked a steep decline in 2012 and 2013, with the lake falling 35' over the past year. As of August 18, 2013, Lake Powell was 109' below full pool (45% of capacity), and was falling at a rate of one foot every six days.


Figure 1. Satellite comparisons of water levels in Arizona and Utah's Lake Powell between 1999 and 2013 show a huge reduction in the amount of water in the lake. Image credit: NASA Earth Observatory.


Figure 2. From October 1, 2012 - July 31, 2013, precipitation over the Colorado River Watershed was about 80% of average. Image credit: Colorado Basin River Forecast Center.

Las Vegas' Water Supply, Lake Mead, Near a Record Low
Downstream of Lake Powell lies Lake Mead, filled in 1936 when Hoover Dam was completed. Lake Mead supplies Las Vegas with ninety percent of its drinking water, and the water level of Lake Mead is expected to fall by eight feet in 2014 due to the lower water flow levels out of Lake Powell ordered on Friday. Lake Mead has fallen by 100 feet since the current 14-year drought began in 2000, and the higher of the two intake pipes used to supply Las Vegas with water from the lake is in danger of running dry. As a result, a seven-year, $800 million project is underway by the Southern Nevada Water Authority to build a third intake pipe that will tap the deepest part of the reservoir. This so-called "third straw" is scheduled to be available late in 2014, which may be cutting it close, if the Colorado River watershed experiences another year of drought as severe as in 2012 - 2013. Southern Nevada has done well to reduce water usage, though--the region's annual water consumption decreased by nearly 29 billion gallons between 2002 and 2012, despite a population increase of more than 400,000 during that span.


Figure 3. Lake Mead water levels from 1938 - 2013 in July show a precipitous drop since drought conditions gripped the Western U.S. in 2000. The Lake Mead photo was taken by wunderphotographer LAjoneson June 29, 2007, when the lake had a "bathtub ring" 109' tall. Water level data from The Bureau of Reclamation.


Figure 4. Workers handle the main drive sections of the tunnel boring machine that is drilling a 3-mile long tunnel through solid rock to supply Las Vegas with water from Lake Mead. The new intake tunnel is designed to maintain the ability to draw upon Colorado River water at lake elevations as low as 1,000 feet above sea level. The lake already has two intake pipes, and the higher of these will go dry when the lake level hits 1050' - 1075'. As of August 2013, the Lake Mead water level was 1106' above sea level, which is 114' below full pool, but 24' above the record low water level of 1081' set in November 2010. Image credit: Southern Nevada Water Authority.

Drought conditions worsen over Southwest U.S. in August
According to the U.S. Drought Monitor, the Western U.S. drought peaked in July 2002, when 79% of the West was in at least severe drought, and 45% of the region was in the two highest categories of drought--extreme to exceptional. However, drought conditions have been steadily intensifying this summer. The August 13, 2013 Drought Monitor report showed that drought conditions in the Western U.S. are now the worst since 2004, with 78% of the West in at least severe drought, and 20% in the two highest categories of drought, extreme and exceptional. The latest U.S. Seasonal Drought Outlook, issued on August 15, calls for drought to remain entrenched over the large majority of the Western U.S. through the end of November.


Figure 5. As of August 13, 2013, severe to exceptional drought gripped nearly all of the Colorado RIver's watershed in Arizona, Utah, New Mexico, Wyoming, California, and Colorado. Image credit: NOAA/NESDIS/NCDC.

Causes of the great Western U.S. drought
It is well-known that natural variations in sea surface temperature patterns, such as seen from the El Niño/La Niña oscillation, can influence storm tracks and can cause prolonged periods of drought. These natural variations likely had a hand in causing the great 2000 - 2013 Western U.S. drought. However, changes in the amount of sea ice covering the Arctic can also have a major impact on Northern Hemisphere atmospheric circulation patterns. We must consider if global warming, which has led to a 50% decline in summer Arctic sea ice extent since 1979, may be altering storm tracks and contributing to drought. In 2004, Lisa Sloan, professor of Earth sciences at UC Santa Cruz, and her graduate student Jacob Sewall published an article in Geophysical Research Letters, Disappearing Arctic sea ice reduces available water in the American west. An accompanying news release explained that their climate models found "a significant reduction in rain and snowfall in the American West” as a result of Arctic sea ice loss:

What they found was a change in atmospheric circulation patterns that caused a small northward shift in the paths of winter storms over western North America. This shift in winter storm tracks resulted in significantly reduced winter precipitation from southern British Columbia to the Gulf of California. In some areas, average annual precipitation dropped by as much as 30 percent. The reductions were greatest along the West Coast, with lesser changes further inland. But even as far inland as the Rocky Mountains, winter precipitation fell by 17 percent.

The sea ice acts like a lid over the ocean surface during the winter, blocking the transfer of heat from the ocean to the atmosphere, Sewall explained. Where the sea ice is reduced, heat transfer from the ocean warms the atmosphere, resulting in a rising column of relatively warm air. The shift in storm tracks over North America was linked to the formation of these columns of warmer air over areas of reduced sea ice in the Greenland Sea and a few other locations.


A follow-up paper by Dr. Sewall in 2005, "Precipitation Shifts over Western North America as a Result of Declining Arctic Sea Ice Cover: The Coupled System Response", used a more sophisticated modeling technique but confirmed the results of the 2004 paper. In a June 2013 interview with climateprogress.org, Dr. Sewall commented:

"I think the hypothesis from 2004 and 2005 is being borne out by current changes. The only real difference is that reality is moving faster than we thought/hoped it would almost a decade ago."


Figure 6. The area of the Western U.S. in drought peaked during 2002 - 2004, but during 2013 has been approaching levels not seen since 2004. Image credit: U.S. Drought Portal.

Western North America drought of 2000 - 2004 the worst in over 800 years
The Colorado River's water woes are due to an extraordinary 14-year drought that began in 2000, which peaked during 2000 - 2004. A 2012 study titled, Reduction in carbon uptake during turn of the century drought in western North America, found that the 2000 - 2004 drought was the most severe Western North America event of its kind since the last mega drought over 800 years ago, during the years 1146 - 1151. The paper analyzed the latest generation of climate models used for the 2013 IPCC report, which project that the weather conditions that spawned the 2000 - 2004 drought will be the new normal in the Western U.S. by 2030, and will be considered extremely wet by the year 2100. If these dire predictions of a coming "megadrought" are anywhere close to correct, it will be extremely challenging for the Southwest U.S. to support a growing population in the coming decades.


Figure 7. Normalized precipitation over Western North America (five-year mean) from 22 climate models used to formulate the 2013 IPCC report, as summarized by Schwalm et al., 2012, Reduction in carbon uptake during turn of the century drought in western North America. The horizontal line marks the precipitation level of the 2000 - 2004 drought, the worst of the past 800 years. Droughts of this intensity are predicted to be the new normal by 2030, and will be considered an outlier of extreme wetness by 2100. The paper states: "This impending drydown of western North America is consistent with present trends in snowpack decline as well as expected in-creases in aridity and extreme climate events,including drought, and is driven by anthropogenically forced increases in temperature with coincident increases in evapotranspiration and decreases in soil moisture. Although regional precipitation patterns are difficult to forecast, climate models tend to underestimate the extent and severity of drought relative to available observations. As such, actual reductions in precipitation may be greater than shown. Forecasted precipitation patterns are consistent with a probable twenty-first century megadrought." Image credit: Schwalm et al., 2012, Reduction in carbon uptake during turn of the century drought in western North America, Nature Geoscience 5, 551-555, Published online 29 JULY 2012, DOI: 10.1038/NGEO1529, www.nature.com/naturegeoscience.

Related posts
Lessons from 2012: Droughts, not Hurricanes, are the Greater Danger, my November 2012 post.

National Geographic has an excellent interactive satellite image that shows the difference in Lake Powell water levels between 1999 and 2013.

How Two Reservoirs Have Become Billboards For What Climate Change Is Doing To The American West, August 12, 2013 climateprogress.org post by Tom Kenworthy.

Scientists Predicted A Decade Ago Arctic Ice Loss Would Worsen Western Droughts. Is That Happening Already?, June 2013 post by Joe Romm at climateprogress.org.

Twenty Cities At Risk of Water Shortages, August 14, 2013 wunderground news post by Nick Wiltgen

References
Sewall, Jacob O., 2005, Precipitation Shifts over Western North America as a Result of Declining Arctic Sea Ice Cover: The Coupled System Response, Earth Interact., 9, 1–23. doi: http://dx.doi.org/10.1175/EI171.1

Sewall, J.O., and L.C. Sloan, 2004, Disappearing Arctic sea ice reduces available water in the American west, Geophys. Res. Lett., 31, L06209, doi:10.1029/2003GL019133. Accompanying news release.

Jeff Masters

Lake Mead - low water (clicks4fun)
Colorado River has been struggling to survive. Predictions of its future are grim in the headlines. Hopefully scientists will figure out how to resolve this bad situation.
Lake Mead - low water
Storm Clouds over Lake Powell, Glen Canyon NRA (catjuice)
Lake Powell, Glen Canyon National Recreation Area, AZ
Storm Clouds over Lake Powell, Glen Canyon NRA

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Quoting 1055. Astrometeor:


Are you two long lost brothers or something?

Edit:



You ninja'd me, now this is weird.


I'm starting to hear the music from The Twilight Zone lol. The crap is contagious I guess
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1059. Gearsts
Well something is getting ejected with the strong trade wind flow to the front. Anything behind will die tonight.
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Quoting 1055. Astrometeor:


Are you two long lost brothers or something?

Edit:



You ninja'd me, now this is weird.


LMAO.
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Quoting 1053. MississippiWx:
K, third time is a charm. Time to go win the lottery.

As long as I get some of the winnings!
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Quoting 1053. MississippiWx:
K, third time is a charm. Time to go win the lottery.
I'm first in line to get your shares. ;)
Member Since: June 30, 2013 Posts: 11 Comments: 7557
Quoting 1049. MississippiWx:


...this is too creepy.



Are you two long lost brothers or something?

Edit:

Quoting 1050. HimacaneBrees:




are ya'll brothers?


You ninja'd me, now this is weird.
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Quoting 1037. kmanislander:
Rotation is solid at the 850 mb level. Not sure if anything significant is going on at the surface as yet. Maybe Ascat will give us a good look later tonight.





925mb to the east of the blob if I'm reading correctly.
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K, third time is a charm. Time to go win the lottery.
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Drew and Cody, lmao, stop posting at basically the same time, it's getting weird.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Quoting 1047. spathy:







It could be 







Or not LOL


Must be a black hole in the central Caribbean pulling everything in LOL
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Quoting 1045. TropicalAnalystwx13:

Don't copy me.
Quoting 1046. MississippiWx:


Omg. Copycat.




are ya'll brothers?
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Quoting 1045. TropicalAnalystwx13:

Don't copy me.
Quoting 1046. MississippiWx:


Omg. Copycat.


...this is too creepy.

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Quoting 1046. MississippiWx:


Omg. Copycat.

Not sure if copied me again internationally or on purpose...
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Quoting 1038. TropicalAnalystwx13:
Nino region 3.4 is plummeting.



Omg. Copycat.
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Quoting 1039. MississippiWx:

Don't copy me.
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I just noticed that not only is the low East of Barbados closing in on the AOI but so is Ex Erin !.

This could be quite a calamitous collission. Erin dive bombing from the NE and the low speeding in on a bee line to the West.
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1043. Patrap
That's a Bad seed.

Wah, wah, waaaaaaaaaah....


Dooodle looo'...







Member Since: July 3, 2005 Posts: 421 Comments: 127628
15-luv. Advantage, Cody.
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Member Since: Posts: Comments:
Nino region 3.4 is plummeting for the time being.

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Rotation is solid at the 850 mb level. Not sure if anything significant is going on at the surface as yet. Maybe Ascat will give us a good look later tonight.

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1036. GetReal
Quoting 1003. moonlightcowboy:
Very weak, low-level steering in the Caribbean. Only a Coriolis motion would drag it a little north in the weak flow, and a very slow-mover would mean great opportunity for intensity especially as it approaches Jamaica and the northwestern Caribbean in the high TCHP.






Just checking in before turning in for the night , and see that we have an interesting blob approaching the central Caribbean. MLC I took a look at that feature coming into the Lesser Antilles. I believe that it will indeed catch up to that larger blob before daylight, and may help light the fuse.
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Quoting 1028. Cat5hit:
Anything new going on in the tropics?


ahh not really I don't believe. but I gotta say that I absolutely love your screen name, handle or whatever its called.
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Figure 3. Lake Mead water levels from 1938 - 2013 in July show a precipitous drop since drought conditions gripped the Western U.S. in 2000. The Lake Mead photo was taken by wunderphotographer LAjoneson June 29, 2007, when the lake had a "bathtub ring" 109' tall. Water level data from The Bureau of Reclamation.

I have a similar image of the Glendo Dam on the N Platte in east central Wyoming, taken about the same time...



The "bathtub ring" at Glendo wouldn't have been so high, but it still must have been extensive for it to show so clearly from as far away as I was...

Quoting 814. Patrap:
..stuck inside these 4 wall's, sent inside forever, never blogging with no one..


"if I ever get outta here..."

One of my faves by Wings...

Quoting 819. victoria780:
I guess the great drought of the 20s and 30s had alot of global warming and co2?
Entirely possible... given the increased industrialization of the globe and the ascent of the gasoline driven engine as the main means of transportation in many parts of the world... there has been a warming trend, though perhaps not as precipitous as seen more recently...

Quoting 887. overwash12:
They might give MSNBC a run for their money!
Dude, get over it. Nobody watches MSNBC for wx news. It's openly, unapologetically and vocally political talk TV. Stop pretending you have anything to do with which political station people watch. You are fooling yourself...
Member Since: October 25, 2005 Posts: 19 Comments: 21537
1032. will40
Quoting 1026. kmanislander:
Who has the yellow crayon ?. LOL


Stewart usually has one im told
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Quoting 1024. spathy:





I would gladly take a penny for every COUI

FBM Spathy channeling MNS criteria lingo.


I took to writing my own discussions on AsOI to me, since the NHC went into laconic mode. Don't do it in caps, though. And don't forget the &&s.
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Quoting 1027. TropicalAnalystwx13:

I do.


We may need it by tomorrow morning unless that feature blows itself out.
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Quoting 1026. kmanislander:
Who has the yellow crayon ?. LOL

I do.
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Who has the yellow crayon ?. LOL
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Quoting 1022. CosmicEvents:
I wish I had a nickel for every eye(including my own) that watched areas of interest all year.

Just one of these would do it for me.
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Quoting 1022. CosmicEvents:
I wish I had a nickel for every eye that watched AOI's of interest all year.


Don't we all ?? :-)

At least you didn't ask for a dime.
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I wish I had a nickel for every eye(including my own) that watched areas of interest all year.
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Quoting 1013. MississippiWx:


I would keep an eye on that area, Kman. If the small low to the east of the islands is able to catch up, it might provide the needed boost to get development going.


I've had both eyes on it for a few days LOL
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Quoting 1015. moonlightcowboy:


I know, Kman, you've had your eye on that awhile now. I've been paying attention. ;)


This certainly has the look about it.

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72 hours watch out!
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Quoting 1013. MississippiWx:


I would keep an eye on that area, Kman. If the small low to the east of the islands is able to catch up, it might provide the needed boost to get development going.


MSWx, honestly though, it seems to have a good boost going already. ;) This one seems to neekin' up on folks.
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Quoting 1009. kmanislander:


That is the low that I was also following for the past 3 days. It may catch up to the feature in the Central Caribbean and impart a little impetus to it with the low it is carrying.
I see a winds coming from the south.
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Quoting 1009. kmanislander:


That is the low that I was also following for the past 3 days. It may catch up to the feature in the Central Caribbean and impart a little impetus to it with the low it is carrying.


I know, Kman, you've had your eye on that awhile now. I've been paying attention. ;)
Member Since: July 9, 2006 Posts: 184 Comments: 29594
1014. Dakster
Quoting 1006. tramp96:


Everybody start your cars and eat more beef

Link


I never stopped....
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Quoting 1011. kmanislander:


I would keep an eye on that area, Kman. If the small low to the east of the islands is able to catch up, it might provide the needed boost to get development going.
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1012. Dakster
Quoting 849. Patrap:
Plus 10 for Taz.

Eggcellent..



You guys crack me up.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
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A want another Jose... the Jose of 1999, not the one of 2011 XD

Our Jose was VERY WET!!!!
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.