Wednesday, September 9, 2009
Dead Pool: Lake Powell, Global Warming, and the Future of Water in the West
by James Lawrence Powell
I previously read and reviewed a book entitled, "A Story That Stands Like a Dam" that covered the battle to save Glen Canyon. The book covered the battle over Glen Canyon well and touched on some of the fallacies used by the Bureau of Reclamation to justify its existence but I wanted something a little more in depth. Thus enters the apocalyptic page-turner of a book "Dead Pool".
Dead pool is defined as when the level of water behind the dam is too low to generate hydroelectric power or to spill water downstream. It is essentially a stagnate body of water and we will have a 50% chance of seeing Lake Powell reach that level by as early as 2017. Why we have gotten to that point is what Powell covers in this book.
One reason is that the recorded water levels measured to decide how to divide up the Colorado River between the upper basin, lower basin and Mexico were taken smack dab in the middle of a 40 year wet cycle and thus too high. The Colorado River was gauged to have 16 MAF (million acre feet) of annual flow. The upper basin received 7.5 MAF, the lower basin 7.5 MAF and Mexico 1 MAF. What we now know is that the average is only 14.6 MAF, which is 1.4 MAF short. This means that in order for the upper basin controlled by the Glen Canyon Dam to deliver its 7.5 MAF to Lake Mead and 1 MAF to Mexico, it will short change itself 1.4 MAF of it's promised 7.5 MAF.
If this weren't bad enough, the Bureau of Reclamation didn't include evaporation losses of over a 1 MAF a year into this equation. Also not included are the effects of global warming which also increased the evaporation losses even more. Although these dams largely are used for irrigation purposes with 80% of the water going towards such, 20% is being pumped to cities in the desert for their primary water source. To give some sense of perspective, an acre-foot of water defined as one foot high of water spread over an acre of land is necessary to support only two urban families per year. As cities have gotten larger due to an abundant water supply, they have required more and more water leaving less for irrigation and power generation needs, the primary reasons the dams were built.
Powell does a good job of laying out the fallacies of trying to irrigate in a desert. Most of the irrigated land is used to grow high water usage crops like forage feeds for livestock that are in surplus already in states where irrigation isn't needed. Irrigation eventually poisons a fertile valley by leaving behind salts that eventually cut production to levels even subsidizing has a hard time keeping at a level where a profit could be made. Never mind that the loans given to farmers to buy the water were never repaid and interest rates were eventually set at 0% for the first 60 years or in other words, longer than the farmer will ever live.
Gradually the scope has changed for the Glen Canyon Dam and preserving the Grand Canyon National Park as described in the act that created national parks and up until recently ignored by the Bureau of Reclamation, has also made a large impact on water levels. Instead of fluctuating water levels based off the power needs of Las Vegas, sandbar levels, endangered species of fish and flora are now of higher importance on the list. The three flushes of the Grand Canyon to rebuild sandbars have largely been a failure (past the first 30 miles) and have done little to save the humpback chub, one of the ten endangered species of fish that called the warm silty waters of the Grand Canyon home. Fortunately, the low waters of Lake Powell have meant that the water is warmer nearer to the generator intakes and thus the river between the dams is warmer has caused the chub to make a temporary comeback. However the continual degradation of the beaches can only be solved by a multi-billion dollar plan to pump silt from above the dam to the river below the dam.
Of course siltation is another big topic of Powell’s book as he discusses how the silt is being trapped by Lake Powell and will eventually fill it up. Although it won't occur in my lifetime, my grandchildren will be dealing with the issue. Already a large silt pile rests against the base of the Glen Canyon Dam where is exerts a magnitude of more force than just water. What happens when this pile gets bigger, definitely within my lifetime, resting against a dam not designed to take a magnitude more force?
Powell makes a very convincing case that there isn't enough water to support Lake Powell, that if global warming gets only as bad as the minimalists say and cities that rely on the water grow as the slowest of forecasted paces, that that much of the time even Lake Mead will only be half full. He goes on to predict that we will have another 'Grapes of Wrath' like exodus on our hands where people will migrate in mass north or east instead of west. The scary part is that this isn't some theory of the future. It actually began five years ago.