category

Archive | Water

Water conservation works. Lake Mead levels have stabilized


Lake Mead will end 2016 only two inches lower than in 2015, despite the drought. This is because, among other things, Nevada and Arizona continue to use less water than their allotment. Las Vegas also recycles all inside water. It flows back into lake Mead and is reused over and over. This does not count against its minuscule 1.8% allotment of water from Lake Mead.

Conservation works. Southern Nevada, Phoenix, and Tucson now use less water overall than they did twenty years ago, despite much larger populations.

As I write this on New Years Eve, it looks like Mead will end 2016 at elevation 1,080 feet and change above sea level, just a couple of inches below where it ended 2015. Maybe the experience of the last couple of years suggests “inexorable” is no longer the right word?

A few things are going on here:

Arizona only took 2.61 million acre feet of water in 2016, 93 percent of its full allotment.
Nevada only took 235,000 acre feet, 78 percent of its full allotment.

Over the last couple of years, the combined conservation efforts of Arizona and Nevada are equivalent to about 8 feet of elevation in Mead – water that is currently sitting in the reservoir.

Resilient thinking. Las Vegas and water usage

A common misconception is southern Nevada and Las Vegas are huge water pigs. The opposite is true. Per capita water use has dropped since 2001, thanks to a smart region-wide water authority that encourages conservation and a world-class system that recycles and reuses every drop of water that goes down a drain or toilet, as well as saving rainwater, by letting it all flow back into Lake Mead where it is reused.

The entire rainwater capture system works by gravity. There are no pumps. Rain is captured in huge basins, flows downhill to water treatment plants, marshlands, Lake Las Vegas, then into Lake Mead. By law, southern Nevada can use 1.8% of water in Lake Mead. However, recaptured water does not count towards that total. It’s one of the most innovative water systems anywhere.

In the early 1990s, southern Nevada was headed towards a water crisis. One problem was there were seven water agencies. They joined together to create the Southern Nevada Water Authority, which shares resources.

The ability to band together to take collective action for the common good is a key to resilience in human systems.

The Southern Nevada Water Authority created a regional framework for the pursuit of conservation, and pursue it Las Vegas did. With publicity campaigns, restrictions on landscaping in new construction, and policies like lawn buy-back programs, Las Vegas residents’ water use began to drop. From 1994 to 2014, per capita water use declined by 36 percent. Conservation soon outstripped population growth, such that total water use peaked in 2002 and has been declining ever since.

From the comments. This is key. Charge more for water and people will use less.

Fun fact – in Nevada, it is legal for a water authority to raise prices with the intent of encouraging conservation in usage. Aggressive pricing of a scarce resource is a key driver in reducing Vegas’ water usage per capita, along with the other policies you mention. In contrast, In California water authorities can only charge for cost of service, which makes it much harder to reduce water usage per capita.

Largest power plants worldwide are hydroelectric

biggest power plants hydro

Hydroelectric is the quiet workhorse of electricity generation. The nine biggest power plants in the world are hydroelectric. Three Gorges in China is the biggest by far, with a capacity of 22.5 GW. (One gigawatt can roughly power 725,000 homes in the US, probably more in China.)

The Kashiwazaki-Kariwa nuclear power plant in Japan has been shut down since Fukushima, thus the top nine are all hydroelectric. Big coal and nuclear plants come close to matching the 6.5 GW output from bottom-ranked Sayano-Shushenskaya Dam but do not surpass it.

Big hydro is indeed renewable energy, however not without environmental issues. Huge dams displace large number of people. The weight of all the water can trigger earthquakes. Eventually the lakes do silt up. And there are other issues too.

Dammed rivers have also impacted processes in the broader biosphere. Most reservoirs, especially those in the tropics, are significant contributors to greenhouse gas emissions (a recent study pegged global greenhouse gas emissions from reservoirs on par with that of the aviation industry, about 4% of human-caused GHG emissions). Recent studies on the Congo River have demonstrated that the sediment and nutrient flow from the Congo drives biological processes far into the Atlantic Ocean, including serving as a carbon sink for atmospheric greenhouse gases.

Large dams have led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, huge losses of forest, wetland and farmland, erosion of coastal deltas, and many other unmitigable impacts.

Severe subsidence in some parts of California Central Valley

Two piers, with hydraulic jacks installed. The red box is the compressor

Two piers, with hydraulic jacks installed. The red box is the compressor

Subsidence occurs when land drops and doesn’t come back. For example, one side of a house drops an inch or so and the rest stays where it is. This will cause drywall cracks, malfunctioning doors and windows, and cracked cement in driveways. More than a couple of inches and there easily could be serious structural damage.

There has been so much groundwater pumping in the Central Valley of California that some areas are having severe, quite possibly dangerous subsidence. Arbuckle, a small town on I-15 in the Sacramento Valley, has had 4-8 inches of subsidence in eight years. That’s enough to endanger water mains, gas lines, canals for water, electric lines, as well as buildings. Unremediated, a house with areas that drop 8 inches in eight years might well be deemed unsafe to live in.

It is possible to save homes by fastening them to piers that go down 30-40 feet into bedrock. We did this on a rental property we owned in southern Utah. There was no choice. And it saved the house. The photo shows part of the operation. The piers are connected to each other by hydraulic jacks. That little red box connects to a GPS inside the house telling the jacks what to do.

Now imagine subsidence like this happenings on roads, canals, lowering some phone poles but not others, and you get an idea what the problem is!

Inelastic subsidence occurs when the structure of a clay is compromised during compaction, to the point where it is unable to expand to its original thickness even when groundwater levels rise. When that layer of clay, or silt, in the underground compresses, ground levels drop.

Subsidence is not uniform. There are certain areas that can drop due to subsidence while the surrounding area stays the same.

You get a lumpy type of dropping going on,” Hull said. “Slumping on roads, stuff like that.”

Hull said this can occur in California from three different factors: tectonic movement, oil and gas extractions, and groundwater extractions.

The drought and accompanying drilling ever-deeper for agricultural water is almost certainly the cause of the subsidence.

Salton Sea imperiled by smart water usage. Say what?

Salton Sea fish kill

Salton Sea fish kill

The Salton Sea, a huge salt water lake in southern California has been fed in modern times primarily by polluted agricultural run off. This causes fish kills. The Sea is also a major migratory stop for birds. Decreased water usage by surrounding farms means less water flows into the Salton Sea. This could lead to an environmental catastrophe as it dries up, nasty toxins are released, and dust storms carry them for miles.

If more water is released into the Salton Sea, then less Colorado River water is available for California, which puts more pressure on the Sacramento Delta, which doesn’t need more stress, thanks for asking.

There are no easy, painless answers here. The State of California or maybe the feds will have to intervene and it will be expensive. There really is no other option.

The problems of the Salton Sea, an inland water body fed by agricultural drainage from the Imperial Valley, are an integral part of the Colorado River story. As we pursue efficiency, agricultural drainage shrinks. And so, therefore, does the Sea.

The most significant problem caused by a dwindling Salton Sea may be a public health issue. As the Sea shrinks, exposed shoreline flats are dust storms waiting to happen, creating filthy air and a public health risk. Importantly, the most vulnerable population here is poor.

The current scheme for reducing water use in Imperial includes a trigger point that would lead to significant reduction in ag runoff and a shrinking sea beginning Dec. 31, 2017. That’s not far away. The water use piece is crucial to balancing California’s water books. Without those Imperial reductions, less Colorado River water would be available to municipal Southern California. A loss of water supply reliability there would increase pressure on the Sacramento-San Joaquin Delta, the other source of Southern California’s water.

So this is a statewide problem, but the poor folk of Imperial are being asked to bear a disproportionate burden in its solution.