One-third of US counties face increased risk of climate-induced water shortage and drought

By mid-century climate change will mean a high or extreme risk of water shortages in 14 states, according to a new study commissioned by the Natural Resources Defense Council.

One-third of U.S. counties will face at least some higher risks of water shortages, with 400 counties at extremely high risk, the report by consulting firm Tetra Tech concludes.  CAP’s Tom Kenworthy has the story.

The report is based on current water use rates extrapolated for expected growth in demand, and water supply projections based on a set of 16 climate models’ estimates of precipitation and temperature by the year 2050.

In part because so many of the counties at greatest risk have large agricultural economies, the disruptions could be great, said Dan Lashof, who directs NRDC’s climate center. “Water shortages can strangle economic development and agricultural production,” he said. “As a result, cities and states will bear real and significant costs if Congress fails to take the steps necessary to slow down and reverse the warming trend”¦.  The only way to truly manage the risks exposed by this report is for Congress to pass meaningful legislation that cuts global warming pollution and allows the U.S. to exercise global leadership on the issue.”

The 14 states cited as most at risk in the report are Arizona, Arkansas, California, Colorado, Florida, Idaho, Kansas, Mississippi, Montana, Nebraska, Nevada, New Mexico, Oklahoma and Texas. Many of the counties at extreme risk are in the Great Plains and Southwest.

— Tom Kenworthy is a Senior Fellow at the Center for American Progress.

Related posts:

Here are some excerpts from the NRDC news release:

More than 1,100 U.S. counties — a full one-third of all counties in the lower 48 states — now face higher risks of water shortages by mid-century as the result of global warming, and more than 400 of these counties will be at extremely high risk for water shortages, based on estimates from a new report by Tetra Tech for the Natural Resources Defense Council (NRDC).The report uses publicly available water use data across the United States and climate projections from a set of models used in recent Intergovernmental Panel on Climate Change (IPCC) work to evaluate withdrawals related to renewable water supply.  The report finds that 14 states face an extreme or high risk to water sustainability, or are likely to see limitations on water availability as demand exceeds supply by 2050. These areas include parts of Arizona, Arkansas, California, Colorado, Florida, Idaho, Kansas, Mississippi, Montana, Nebraska, Nevada, New Mexico, Oklahoma, and Texas. In particular, in the Great Plains and Southwest United States, water sustainability is at extreme risk.

The more than 400 counties identified as being at greatest risk in the report reflects a 14-times increase from previous estimates. For a look at county- and state-specific maps detailing the report findings (including a Google Earth map), go to and

While detailed modeling of climate change impacts on crop production was beyond the scope of the Tetra Tech analysis, the potential scale of disruption is reflected based on the value of the crops produced in the 1,100 at-risk counties. In 2007, the value of the crops produced in the at-risk counties identified in the report exceeded $105 billion.  A separate study compared the Tetra Tech data with county-level crop production data from the U.S. Department of Agriculture; state-specific fact sheets outlining the potential agricultural impacts may be found at….

Sujoy Roy, principal engineer and lead report author, Tetra Tech, said: “The goal of the analysis is to identify regions where potential stresses, and the need to do something about them, may be the greatest. We used publicly available data on current water withdrawals for different sectors of theeconomy, such as irrigation, cooling for power generation, and municipal supply, and estimated future demands using business-as-usual scenarios of growth.  We then compared these future withdrawals to a measure of renewable water supply in 2050, based on a set of 16 global climate model projections of temperature and precipitation, to identify regions that may be stressed by water availability.  These future stresses are related to changes in precipitation as well as the likelihood of increased demand in some regions.”

Water withdrawal will grow by 25 percent in many areas of the U.S. including the arid Arizona/New Mexico area, the populated areas in the South Atlantic region, Florida, the Mississippi River basin, and Washington, D.C. and surrounding regions.

Estimated water withdrawal as a percentage of available precipitation is generally less than 5 percent for the majority of the Eastern United States, and less than 30 percent for the majority of the Western United States. But in some arid regions (such as Texas, the Southwest, and California) and agricultural areas, water withdrawal is greater than 100 percent of the available precipitation. In other words, in many places, water is already used in quantities that exceed supply.

A summary of the report and related links are available at


21 Responses to One-third of US counties face increased risk of climate-induced water shortage and drought

  1. Peter Mizla says:

    New England faces the least water shortages for quality in the future-though southern New Hampshire and Boston’s outer western suburbs will face some issues (according to the map)

    Our problems in New England will be sea rise- and its associated problems- seepage of salt water into lowlands and vulnerable wetlands.

    The migration of certain specialty agriculture like blueberry’s, maple syrup, and in the fishing industry’ lobster, flounder & cod will migrate north.

    Invasive plant species and migrating flora from warmer climates will present new problems.

    Our autumn colors will dim as more southern species supplant sugar maples-as they move north.

    The ski industry has been in decline for years in southern New England.
    It has moved into Vermont New Hampshire and Maine- though in some years recently the industry has had ‘brown’ winters.

  2. Daniel Ives says:

    A very interesting (and indeed scary) chart.

    If I read things correctly, this study is based on climate models of precipitation and thus did not include the effects of US water management policies (anyone please correct me if I’m wrong). I bring this up because if this is included, I believe far more counties would face shortages. For example, look at the Colorado Rocky Mountains. Things look pretty good on the map, but look at the thirsty regions to the west and east of the Rockies. These regions will demand that more water be made available to them, meaning that Rocky Mountain counties will have to use less and allow more to flow downstream, creating an artificial water shortage in those counties. Just something to think about. Thanks for the post, Joe.

  3. BB says:

    I was also wondering…Is there no place in the US that would end up with an ‘increased’ water supply sustainability scenario given climate change?

    I’m not suggesting this negates an approaching water shortage danger for the US…But, I was surprised to see from this map that absolutely everywhere had either a ‘low’ negative impact through ‘extreme’ negative impact, with perceivably no region potentially being in better straits regarding water supply, considering the possibilities that more than a few areas may be receiving a net increase of annual rainfall (dangerous flooding or not) in the decades to come.

    I recognize that annual rainfall does not comprise the entire ingredient list for sustainable water supply, but for local resevoir replenishment, it’s a big participant.

  4. Dana says:

    Hey Tetra Tech, that’s my company! So you know the report is accurate :-) We’re the #1 ranked environmental consulting firm on water issues.

    Disturbing conclusions.

  5. fj2 says:

    Having absolutely no expertise on this, it does seem that the Intergovernmental Panel on Climate Change (IPCC) models have been overly conservative and current observations may be even more critical to determining how this crisis is actually unfolding.

  6. I think an equally critical question is how this climate-change induced drought will affect Mexico and Central America. The computer models for Texas and Arizona are frightening, but what about down south? What is the limit for sustainability in this region? Is there a scenario where this region becomes uninhabitable? And, if so, what are the consequences? How quickly does this change happen?

    The idea of Mexico’s population migrating en masse to the United States needs to be addressed. In fact, migration would be deeply disruptive in a world with runaway global warming.

    And, still, demand for fossil fuels rise and rise. Consumption continues to rise and rise. Nobody in charge is interested in doing anything but chip at the edges (Obama’s 17% reduction by 2020) or ignore reality completely (Republicans). I’d really not like to panic about this issue, but I’m not seeing a lot of hope right now.

  7. Prokaryotes says:

    Climate Change: Risks to U.S. Water Supplies Will Increase

  8. Michael Tucker says:

    “…in some arid regions (such as Texas, the Southwest, and California) and agricultural areas, water withdrawal is greater than 100 percent of the available precipitation. In other words, in many places, water is already used in quantities that exceed supply.”

    In other words those farming regions are drastically drawing down their aquifers at this time, not 40 years in the future. In 2050 those regions will become dust bowls. The only way to avoid disaster is to make basic changes to our water policy and infrastructure. Water needs to be priced to reflect the cost of delivery and to encourage conservation. Agriculture and industry must reduce water waste now! Leaky water systems must be repaired. More efficient irrigation methods must be used. Water recycling must begin. It is time to treat water as a precious resource that could disappear in many regions. Some regions have begun to take steps to protect what they have. For instance the states that border the Great Lakes have pledged to NOT ALLOW Great Lakes water to be transported through their states. That water is only for them and Canada.

  9. Prokaryotes says:

    7 Steps To Survive the Coming Economic Collapse – From Water Shortage to Cannibalism

  10. Peter Mizla says:


    I thought I was gloomy- you make me feel like Mr. Sunshine.

  11. Prokaryotes says:

    When i do not agree with all in this article, the main purpose is to see this in the prospect of climate change. When we today see temperature extremes around 110 F, what do people expect in 5,10 or 20 years?

  12. Peter Mizla says:

    The populace in the USA hit hard by the infernal this summer are coping- those with CA- in their homes, cars and offices are only momentarily affected.

    Those who are old, and poor (or both) feel this heat the most.

    Hundreds are drowning in Russia- Europeans historically have used CA far less then in this country.

    When the heat begins to last for longer periods of time in temperate climates- it will begin to have a psychological impact on peoples ability to function.

    Droughts, water shortages, intense storms, brownouts, agricultural failure are likely to increase as the decades progresses.

    AS has been said here- when will an an event push us over the cliff socially and mentally? That is the real question many have here.

    Only someone who is in total denial of everything would not see the many increasing bizarre climatic events beginning to now ‘explode’ globally- and this seems after we passed 390ppm- at 400ppm they will increase.

    As Bob Dylan once said- ‘the Times are A Changing’ and not for the better.

  13. Prokaryotes says:

    Peter Mizla some believe they can prevent a pearl harbor by geoengineering with the use of chemicals.

  14. Prokaryotes says:

    Peter Mizla some believe they can prevent a pearl harbor by engineering with the use of chemicals.

    Post #50 of global warming news from the 20th

  15. homunq says:

    It is certainly a lot easier to find such maps (precipitation or temperature, projected averages or extremes) for the US. I have not been able to find global maps with a resolution of more than a couple of pixels for a small country (I mean small as in Belize or Israel, not Monte Carlo or Singapore).

    If anybody knows where I could find such data (including scientific papers which are behind some paywall), I’d be grateful for the link.

  16. Peter Mizla says:

    New Scientist is not a favorite site of mine; Prokaryotes

    Geo engineering at least now is not a viable option for GW

  17. Maybe I could put in a quick plug for wind energy, which combats this problem on two fronts, requiring virtually no water to generate electricity and also displacing greenhouse gas emissions … more info here:

  18. Leif says:

    I would like to give a shout out for an unappreciated solution to many climatic problems. The Family Garden.

    Energy from the sun to food for your table at your fingertips. No driving. Better quality. Trading stock. No shipping costs. No packaging costs or waste. Less water consumption. Rewarding use of time on many fronts.

  19. fj2 says:

    18. Leif, Yes! “The Family Garden”

    Definitely a whole systems solution!

  20. fj2 says:

    #19. fj2 (continued)

    Probably a lot of the real solutions reside in light-weighting heavy machinery and industry, the built environment, and transportation; and, people doing things for themselves; and of course, living with meaning and passion; pretty simple stuff, not necessarily easy to achieve.

  21. Richard Brenne says:

    The map is roughly what one would expect, with already dry places like east of the Rockies in their rain shadow being dry, Arizona and Texas (in California and New Mexico mountain rain shadow) being dry, etc.

    It’s odd to find the best ratings including southern Louisiana and southern Florida, which are going to have more problems with sea level rise sooner and essentially forever than any other places in America.

    Roughly the Ogallala Aquifer that is being seriously depleted by pumping up water for sprinkler irrigation has much of the worst rating as one would expect – has aquifer depletion been factored into this study?

    Basically wet places and places with large rivers and lakes including all of the Great Lakes do best, also North does better than South and East than West, except for west of the entire Cascade Range, which does okay except for the populous Multnomah (Portland) and Washington (Beaverton) counties where I live.

    But I’d like to see studies like this with the most full-cost accounting, which would find: Places vulnerable to sea level rise infiltrating water tables will do worse than this map shows; places with aquifer depletion might do worse than this map shows; places with junior water rights will do worse, but if chaos ensues being upstream could be better than being downstream. Also how much investment is made in upgrading water infrastructure will be key.

    Then the people of those counties in the deepest red will likely visit those in the white-colored counties, probably permanently. If you don’t like certain in-laws, instead of a home addition you might want to consider some square footage demolition.

    Big backyard swimming pools, long car washes, hosing off driveways and endless watering of lawns will finally be seen for what they are.