Running Dry? California Water Supply at Risk

View of Lake Mead on 9/9/10 (Image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center)

Lake Mead is the largest reservoir in the country.  It’s located on the Colorado River, which provides water for about 27 million people in seven states, including millions of Californians.  In fact, California gets more than a trillion gallons of water from the Colorado River each year, directly from Lake Mead via the Colorado River Aqueduct which snakes across the desert.  Eighteen million people in Southern California are dependent on the Colorado for 40% of their water.  And for some agricultural operations, that percentage is more like 100.  Needless to say, it’s a critical source of water.

The thing is, after 11 years of dry conditions in the region, Lake Mead dropped to its lowest level ever in October.  And so far, it’s stayed there.  Since Hoover Dam was completed in the 1937 the water level has never been so low.  As of today, it’s at 38% of capacity.  And it’s not just Lake Mead that’s low.  The whole Colorado River storage system is at just 55% of capacity, so forget just filling it up with water from upstream.  Of course, winter’s on it’s way, and with that, precipitation, so the lake shouldn’t stay quite so low for long.  And, thanks to a wet year, Northern California’s reservoirs are doing well.

But when you think about this water shortage in terms of population trends and the changing climate, the future for water in the Southwest looks grim.  Population areas supplied by the Colorado River are some of the fastest growing in the country. So demand is going up.  At the same time, scientists and water managers say the supply will go down.  The region is expected to get warmer and drier in the coming decades, which means less precipitation, and more specifically, less snow.  Which means that of the precipitation that does come, more will come as rain, which is harder to capture and store for use throughout the dry summer months.

In fact, studies show that the river’s flow is likely to decrease 10-15% in coming decades due to climate change, according to the Bureau of Reclamation’s Terry Fulp, and, he said, the demand is already outpacing the supply.

“The supply and demand curves have crossed,” he told me last May.

The question of just how long the Colorado River can continue meet the needs of seven states with growing populations, depends on how quickly those supply and demand curves are diverging.   Scientists have given varying estimates of when Lake Mead will go dry, but recent studies estimate a 50-50 chance that it could happen before 2057.  (Earlier studies had estimated it as soon as 2021.)   The state’s population is expected to increase by half, to nearly 60 million, by 2050.

So, Californians, what happens then?  And what should we be doing now to prepare?  It might be worth thinking about.  In 2060, taking shorter showers and turning off the water when you brush your teeth might not be enough.

Running Dry? California Water Supply at Risk 2 February,2018Gretchen Weber

8 thoughts on “Running Dry? California Water Supply at Risk”

  1. I doubt that most people who water their gardens and wash their cars in Las Vegas actually realize that in all likelihood, the water pouring out of their sprinkler systems and garden hoses originated as snow falling in the Colorado Rockies. And until more citizens in desert cities like Vegas come to grips with this reality — and the brute fact that we are withdrawing more water from the Colorado River system than nature is actually putting into it over the long run — we will make little progress.

    Also, just FYI: the original image you used for this post did come from NASA as your credit indicates. But the actual version you’ve used here appears to be one that I processed and cropped specifically for my blog, CEJournal. I spent a good deal of time getting it just right, so credit where credit is due . . .

    1. Hi Tom,
      Thanks for your comment, and for the image. I apologize for the initial incomplete credit. Thanks for speaking up. It’s been corrected now, and we added a link from it to your post. Please let us know if you’d prefer that we take it down.

  2. You would be surprised what us life long residents of Las Vegas know about our water supply. We know where it comes from and where most of that water is going.

    Las Vegas gets a very small percentage of the water that flows through Lake Mead. Arizona, California and Mexico are using much more of this water then Las Vegas does per capita.

    Another thing that most don’t know is even though Las Vegas has grown our water usage per capita has dropped. We have been on special watering schedules and conservation methods for years. Most of our golf courses and water features at the hotels are recycled water instead of just dumping it down the drain.

    If you want to help the water problem, look downstream at the abuse and waste in the lower states. They seem to think there is an endless supply of water and waste it everyday.

    Another problem is the water being held at Lake Powell. It was predicted when that damn was built at Powell that there could be problems down stream yet they built it anyway. A lot of the problems have to deal with politics and not the usage in the desert of this water.

    We all need to conserve but people need to start looking at all usage, not just the small amount being used in Las Vegas.

    1. Thanks for this information Lee! I suppose it’s too easy to beat up on Vegas because of the appearance of excess there.

      In any case, there is one fundamental fact that people of the region — all of us — have not yet come to grips with: The Colorado River is over-subscribed. The waters were allocated to the states of the Upper and Lower Basins back in the 1920s based on flows that were way above the long-term average. Now, the flows are considerably lower, which means we are taking more from the river than is actually there. Powell and Mead have saved our butts for awhile. But barring a big increase in precipitation and flows, which climate scientists say is unlikely, a day of reckoning is eventually coming.

  3. There is a vast climate difference between the east and the west even in relatively recent history. The Colorado River Drainage appears to have been through a relatively recent “wet” period and historically has experienced long periods of dry years. The low water production was and is to be expected. It is indeed over subscribed to put it nicely.
    Water Agencies, Water Commissions, whatever political name you want to put on them have continually oversold water rights for any river drainage or hydrological unit that they are accessing. Some states such as California have given water rights at levels that 150% of average flow. When politicians and engineers are together rivers and the envrironment will be destroyed. Take a look at the Metropolitan Water District and its actions if you want confirmation. How many river systems and local environments will they be allowed to destroy?
    Southern California is notorious for simply wasting what limited precipitation they receive. With the help of the USACE they have destroyed rivers and streams that would have allowed some semblance or recharge and balance to the environment is properly utilized. Instead they treat stormwater as a disease laden product that must be immediately discharged into the ocean.
    It is time for southern California to stop misappropriation of water from other hydrologic units. They have continued to allow illegal and ill advised population of an environment that is naturally restricted. As long as politicians crave power and engineers crave money we will have these problems.

  4. A little perspective on the importance of Colorado River supplies to California. Of the approximately 40 million acre-feet (maf) of water we used in the state in 2005 (80% to agriculture), 4.5 maf came from the Colorado. Of that, the vast majority served to irrigate the Imperial Valley, formerly known as the Colorado Desert.

    For years, California used more than its allotment under the Colorado River Compact. Now that Arizona and Nevada are more built out and have the necessary infrastructure in place, they are using more of their share.

    We know now that the Compact had some serious flaws. First, it over-allocated the river: combined rights exceed discharge in most years. Second, nature’s share was exactly zero. The result has been that the Colorado rarely flows into the sea. The result has been the ecological collapse of the vast marsh called the Colorado Delta, and the estuary known as the Gulf of California or the Sea of Cortez.

    Indeed, we need to do more than take shorter showers. We need to adapt to the changing climate by reforming our governance of water, taking into account natural limits.

    1. Glad you brought that up, Matt, because our LA Bureau Chief, Krissy Clark, just returned from the Imperial Valley and is preparing a report on how that region depends on the Colorado. Look for that next week.
      We know, of course, that California as a whole is much more reliant on the Sierra snowpack and the Sacramento River system.
      Thanks for weighing in (for those who don’t know, Matt is an analyst with the Pacific Institute in Oakland, which specializes in water studies)

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