Friday, February 8, 2013

The technology of water

Few people in the industrialized world pay much attention to the water they drink;  but it's becoming more and more of a problem to get it.  (Witness the infamous Las Vegas water grab that took everyone by surprise a few years ago, and is still unfolding.)  Having lived and traveled extensively in the Third World for many years, I'm well aware of how precarious existence is in many areas, where water of any sort is hard to get, and purified drinking water is, for many, only (and literally) a pipe-dream (because there are no pipes to convey it to them).

I was therefore pleased to read a very useful overview of the water supply and consumption dilemma we face here in North America.  Here's an excerpt.

It's well to remember that most of the US west of the Mississippi ranges from relatively dry to very arid, to desert, to lifeless near-moonscapes. The number of people that could be supported by the land, especially in the Southwest, was always small and concentrated along the riverbanks. Tribal clusters died out with some regularity. And that's the way it would have remained, except for a bit of ingenuity that suddenly loosed two powerful forces on the area: electrical power, and an abundance of water that seemed as limitless as the sky.

In September of 1935, President Roosevelt dedicated the pinnacle of engineering technology up to that point: Hoover Dam. The dam did two things. It served as a massive hydroelectric generating plant, and it backed up the Colorado River behind it, creating Lake Mead, the largest reservoir in the country.

Early visitors dubbed Hoover Dam the "Eighth Wonder of the World," and it's easy to see why. It was built on a scale unlike anything before it. It's 725 feet high and contains 6 million tons of concrete, which would pave a road from New York to Los Angeles. Its 19 generators produce 2,080 MW of electricity, enough to power 1.75 million average homes.

The artificially created Lake Mead is 112 miles long, with a maximum depth of 590 feet. It has a surface area of 250 square miles and an active capacity of 16 million acre-feet.

Hoover Dam was intended to generate sufficient power and impound an ample amount of water, to meet any conceivable need. But as things turned out, grand as the dam is, it wasn't conceived grandly enough... because it is 35 miles from Las Vegas, Nevada.

Vegas had a permanent population in 1935 of 8,400, a number that swelled to 25,000 during the dam construction as workers raced in to take jobs that were scarce in the early Depression years. Those workers, primarily single men, needed something to do with their spare time, so the Nevada state legislature legalized gambling in 1931. Modern Vegas was born.

The rise of Vegas is well chronicled, from a middle-of-nowhere town to the largest city founded in the 20th century and the fastest-growing in the nation – up until the 2008 housing bust. Somehow, those 8,400 souls turned into a present population of over 2 million that exists all but entirely to service the 40 million tourists who visit annually. And all this is happening in a desert that sees an average of 10 days of measurable rainfall per year, totaling about 4 inches.

In order to run all those lights, fountains, and revolving stages, Las Vegas requires 5,600 MW of electricity on a summer day. Did you notice that that's more than 2.5 times what the giant Hoover Dam can put out? Not to mention that those 42 million people need a lot of water to drink to stay properly hydrated in the 100+ degree heat. And it all comes from Lake Mead.

So what do you think is happening to the lake?

If your guess was, "it's shrinking," you're right. The combination of recent drought years in the West and rapidly escalating demand has been a dire double-whammy, reducing the lake to 40% full. Normally, the elevation of Lake Mead is 1,219 feet. Today, it's at 1,086 feet and dropping by ten feet a year (and accelerating). That's how much more water is being taken out than is being replenished.

This is science at its simplest. If your extraction of a renewable resource exceeds its ability to recharge itself, it will disappear – end of story. In the case of Lake Mead, that means going dry, an eventuality to which hydrologists assign a 50% probability in the next twelve years. That's by 2025.

Nevadans are not unaware of this. There is at the moment a frantic push to get approval for a massive pipeline project designed to bring in water from the more favored northern part of the state. Yet even if the pipeline were completed in time, and there is stiff opposition to it (and you thought only oil pipelines gave way to politics and protests), that would only resolve one issue. There's another. A big one.

Way before people run out of drinking water, something else happens: When Lake Mead falls below 1,050 feet, the Hoover Dam's turbines shut down – less than four years from now, if the current trend holds – and in Vegas the lights start going out.

There's more at the link.  Interesting and recommended reading.



Billll said...

It's better than that. The Hoover Dam was originally built to supply power and water to Los Angeles, which it still does. Thanks to the interconnection of power grids, the entire 3-state region is tied together, and the loss of the Hoovers power would likely cause rolling blackouts all over the area.

Interestingly the worlds second largest deposit of "clean" coal is a short distance away in southern Utah. Can't use it though. It was declared off limits in return for a political contribution to Bill Clinton in the mid 90s.

diesel smoke said...

It will all be OK.
They are building a solar power plant just out side of town.;)

Anonymous said...

I'm sure California grab Colorado water makes this look puny. Ask Farm Dad.


Well Seasoned Fool said...

As said in the West, "Whiskey is for drinking, water is for fighting'>

On a Wing and a Whim said...

You know, I hear all this worry about them running out of water. You know what I don't hear? Any noise about making a scarce resource more expensive. In fact, we pay about twice per month in TN compared to the Las Vegas rate for our water consumption, and let's not even get started on Phoenix's proud claim that they're the fifth-cheapest city in the nation for water rates.

Very like our national government, the politicians are holding a scarce resource as cheap and limitless while trying to grab for more power to keep the party going. When it runs out, it's all gone... but no use worrying about that when they can kick the can just a little further down the road for now.

joewarrant said...

I strongly recommend a history of dam building and water in the American West by Marc Reisner, "Cadillac Desert"

Toejam said...

My daughter and I went to the Hoover Dam a couple of years ago. Mid July is not the time of year to go there. Trust me.

The new bridge, which filters traffic away from the dam was just being completed.

The dam and its infrstructure are not only massive, but the "art deco" facade, ingravings and inlays are absolutely spectacular.

There's even a large plaque dedicated to a dog which was killed when run over by a constriction truck.

Most of the plaques are solid Bronze or Brass.

Unknown said...

Nevada is allocated less than 24% of the power generated by Hoover Dam. That turns out to be 8.8% of the peak power needed on a summer day. The lights will not got out (and most of the casinos on the strip have co-generation of power--they can power themselves).

Nevada has 0.3 million acre feet per year (MAFY) allocation of Colorado river water. Arizona has 3.85 MAFY and California has 4.4 MAFY. Lake Powell, when it's full, loses 0.86 MAFY of water through evaporation but mostly through ground seepage.

Las Vegas has had water issues for quite awhile now, but they've also been pretty good about conserving. The Las Vegas stip hotels and golf courses only use 3% of the water resources for the whole valley. Through waste water treatment and return to Lake Mead, the valley was able to increase its allocation to 0.39 MAFY (30% increase).

Las Vegas will be in dire trouble if Lake Mead runs out of water, but they are certainly not more than a minor cause. Water levels could be improved just by cutting the losses of Lake Powell through lowering Lake Powell to its lowest possible levels.

The real trouble was water sharing agreements based on absolute amounts that were set during a period of above average flow years. That's why the Colorado river hasn't reached the ocean since 1998.