Over Labor Day I took my wife to Las Vegas for her birthday to see the Cirque du Soliel show “O”, the Hoover dam and experience Vegas. She’d never been before. And it is a milestone birthday. We had a nice trip. The “O” show is all it is said to be. Another spectacular event! The hoover dam is an amazing 80 year old structure, designed to hold water for Arizona, California and Nevada, as well as make some power. Of course all three have long outgrown the reservoir. And the level drops each year to where it is 300 feet below its height less than 15 years back. A colossal feat of engineering that led to huge development in the arid west. The nearby Boulder City was created to build the dam. Las Vegas would not exist without its water. Water in the desert! The Anasazi’s would be amazed.
This month’s Journal for AWWA has several articles devoted to direct potable reuse (DPR). Total Water Solutions is the moniker that AWWA has tapped lately as the organization has moved to the message that water sources cannot be separated. California believes that 40% of its urban water use can be recycled to direct potable reuse, which can address a lot of the drought concerns for urban users (11% of California’s water use). The technology is available to make DPR a reality. The concerns involve insuring system reliability (i.e. redundancy in processes), and public perception of DPR. As I noted in a prior blog, there are two cities in Texas already doing DPR. There are several places in California doing indirect potable reuse (IPR) which basically involves injected the water into an aquifer or releasing it in an upstream reservoir. The treatment is basically the same for both but the separation is creates a different public opinion. One that is not so different than discharging wastewater to rivers that serve as water supplies downstream. Both IPR and DPR were unheard of as ideas outside southern California until more recently. But in the past several years, both have seen a significant change in Texas, California and Florida. Water-logged south Florida has looked at 5 IPR projects in the past 7 years, and has a couple reuse ASR systems. Should drought conditions return, these projects may not be so far-out (note we are at 25% normal rainfall in southeast Florida – but water use is 10% below 2005 levels).
We are all aware of the major drought issues in California this year – it has been building for a couple years. The situation is difficult and of course the hope is rain, but California was a desert before the big water projects on the 1920s and 30s. Los Angeles gets 12 inches of rain, seasonally, so could never support 20 million people without those projects. The central valley floor has fallen over 8 feet in places due to groundwater withdrawals. Those will never come back to levels of 100 years ago because the change in land surface has collapsed the aquifer. But the warm weather and groundwater has permitted us to develop the Central Valley to feed the nation and world with produce grown in the desert. The development in the desert reminds me of a comment I saw in an interview with Floyd Dominy (I think), BOR Commissioner who said his vision was to open the west for more people and farming, and oversaw lots of projects to bring water to where there was none (Arizona, Utah). The problem is that the west never head much agriculture or population because it was hot, dry and unpredictable – hence periodic droughts should be no surprise – the reason they are a surprise is that we have developed the deserts far beyond their capacity through imported water and groundwater. Neither may be reliable in the long run and disruptions are, well, disruptive. Archaeologist Bryan Fagan traced the fall of Native American tribes in Arizona to water deficits 1000 years ago.
Yet policymakers have realized that civil engineers have the ability to change the course of nature, at least temporarily, as we have in the west, south, Florida. I often say that the 8th and 9th wonders of the world are getting water to LA over the mountains and draining the southern half the state of Florida. I have lived in S. Florida for 25+ years and am very familiar with our system. The difference though is that we have the surficial Biscayne aquifer and a rainy season that dumps 40 inches of rain on us and LA doesn’t (as a note of caution, for the moment we are 14 inches below normal in South Florida – expect the next drought discussion to ensue down here in the fall). The biggest problems with the Everglades re-plumbing are that 1) no one asked about unintended consequences – the assumption was all swamps are bad, neglecting impacts of the ecosystem, water storage, water purification in the swamp, control of feedwater to Florida Bay fisheries, ….. 2) one of those unintended consequences is that the recharge area for the Biscayne aquifer is the Everglades. So less water out there = less water supply along the coast for 6 million people 3) we lowered the aquifer 4-6 ft along the coastal ridge, meaning we let saltwater migrate inland and contaminate coastal wellfields 4) we still have not figured out how to store any of that clean water – billions o gallons go offshore every day because managing Lake Okeechobee and the upper Everglades was made much more difficult when the Everglades Agricultural Area was established on the south side of Lake Okeechobee, which means lots of nutrients in the upper Everglades, and a lack of place for the lake to overflow, which meant dikes, more canals, etc. to deal with lake levels.
The good news is that people only use 11% of the water in California and Florida, and that Orange County, CA and others have shown a path to some degree of sustainability (minus desal), but the real problem is water for crops and the belief that communities need to grow. When we do water intensive activities like agriculture or housing, in places where it should not be, it should be obvious that we are at risk. Ultimately the big issue it this – no policy makers are willing to say there is “no more water. You cannot grow anymore and we are not going to send all that water to Ag.” Otherwise, the temporary part of changing nature will come back to haunt us.