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US DOI report highlights impacts of climate change on Western water resources

Projected median temperature change in °F (of 112 climate projections) over the Western United States, 2070–2099 relative to 1950–1979. Source: DOI. Click to enlarge.

The US Department of the Interior released a report that assesses climate change risks and how these risks could impact water operations, hydropower, flood control, and fish and wildlife in the western United States. The report to Congress, prepared by Interior’s Bureau of Reclamation, represents the first consistent and coordinated assessment of risks to future water supplies across eight major Reclamation river basins: the Colorado, Columbia, Klamath, Missouri, Rio Grande, Sacramento and San Joaquin, and Truckee river basins.

The report, which responds to requirements under the SECURE Water Act of 2009, details several increased risks to western United States water resources during the 21st century. Specific projections include:

Projected median percentage precipitation change (of 112 climate projections) over the Western United States, 2070–2099 relative to 1950–1979. Source: DOI. Click to enlarge.
  • a temperature increase of 5-7 degrees Fahrenheit;
  • a precipitation increase over the northwestern and north-central portions of the western United States and a decrease over the southwestern and south-central areas;
  • a decrease for almost all of the April 1st snowpack, a standard benchmark measurement used to project river basin runoff; and
  • an 8 to 20% decrease in average annual stream flow in several river basins, including the Colorado, the Rio Grande, and the San Joaquin.

The report notes that projected changes in temperature and precipitation are likely to impact the timing and quantity of stream flows in all western basins, which could impact water available to farms and cities, hydropower generation, fish and wildlife, and other uses such as recreation.

Click to enlarge.

To develop the report, Reclamation used original research and a literature synthesis of existing peer-reviewed studies. Projections of future temperature and precipitation are based on multiple climate models and various projections of future greenhouse gas emissions, technological advancements, and global population estimates. Reclamation will develop future reports to Congress under the authorities of the SECURE Water Act that will build upon the level of information currently available and the rapidly developing science to address how changes in supply and demands will impact water management.

Water is the lifeblood of our communities, rural and urban economies, and our environment, and small changes in water supplies or the timing of precipitation can have a big impact on all of us. This report provides the foundation for understanding the long-term impacts of climate change on Western water supplies and will help us identify and implement appropriate mitigation and adaptation strategies for sustainable water resource management.

—Interior Secretary Ken Salazar

Impacts to water are on the leading edge of global climate change, and these changes pose a significant challenge and risk to adequate water supplies, which are critical for the health, economy, and ecology of the United States.

—Reclamation Commissioner Mike Connor

The Bureau of Reclamation is the largest wholesaler of water in the country, providing water to more than 31 million people and to one out of five Western farmers for irrigation of more than 10 million acres of farmland. Reclamation is also the second largest producer of hydroelectric power in the western United States with 58 power plants generating nearly a billion dollars in power revenues and producing enough electricity to serve 3.5 million homes.




The precip pattern points to the obvious long term solution, build an aquaduck system from north east to south west...


The San Joaquin and the Sacramento will be flooding this year from extreme precipitation and a huge snowpack, not decreasing precipitation. Almost all CA reservoirs have been releasing waters in anticipation of a big melt. The precipitation has been very above average for several years now. So much for GW-induced drought. Better luck next time.


It is not year to year but the longer term trend. We will get a year of above normal and then several years of below, the trend is below.


GdB...Why not divert 80% of the Mississippi River from just North of New Orleans to California and drop/sell a few million barrels on the way?

Use the remaining 20% build in a deep canal to the GOM for shipping.

Don't know exactly what would be the effect on the GOM. It may turn to pure Oil and wastes after 50 years or so. It may the worth to try to see what happens?.


Any thoughts on tapping the Red River of the North? With the way that floods every year maybe we could solve two problems at once.

Nick Lyons


The precipitation has been very above average for several years now.

Not so. US Southwest has been in the throes of a multi-year drought. Lake Mead (Colorado River) water level has been falling since 2000, and has been below drought level since 2005. Check out the chart at:

One wet year doesn't indicate a trend.


Funny. Guys like Salazar and Mike Conner still march to the outdated alarmist agenda - and make fools of themselves in the face of the actual facts.

Last year's Western States snowpack was 137% normal. This year is 138%. Total precipitation is 124% average.

The more the old school alarmists cling to their AGW theory - the more foolish they look:

Message: Time for a NEW STORY!


Climate change can bring more of everything, more floods, more droughts, stronger hurricanes and more tornadoes. We can have more clouds but less rainfall. The atmosphere and climate are in a delicate balance and you do not want to fool with Mother Nature.


Agreed SJC... And man's emission of CO2 comprising 0.00291% atmosphere has not pushed Mother's Nature beyond natural variability. Change is natural!


You have human induced change riding on top of natural variation. I am not ready for the sum of those two factors and the effect. I am not ready to gamble with humanities future.

I don't get involved in these circular "debates". Using less fossil fuel is its own reward for SO many reasons. If people can not see that, then there is no reason to discuss it, because they will never get it anyway. They are determined not to get it.

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