If You Ever Wondered What "Reservoir Siltation" Means Check These Pics!

[hatrack]

This is the head of Lake Powell, about 150 miles upstream from the dam. If you look for the white mineral stain on the low cliffs surrounding the silt bar and river, that's how high the water level used to be.

The Colorado River is a river once again for about 30 miles north of the bridge. It used to be that you had to break out the outboard and putt-putt down from once you ran the Big Drop rapids in Cataract Canyon. No longer. There's now current well past the downstream tip of the silt bar in the next-to-last photograph.

The important thing to remember when you look at these photos is that just four years ago, this was all under water. Boats & jetskis were whizzing back and forth from the marina that sat where the empty concrete rectangle does today (in the fourth picture down).

Sedimentologists estimate that the silt island you see here is about 150 feet thick above the original river channel.

http://rosebud.moenkopi.net/pics/hite/hite1.html

[nothingshocksmeanymore]

1. Damn that's amazing..and to think of the population growth in areas

dependent on that water is just staggering...developers were able to do what they wanted in CA and AZ without plans for water...staggering

[phantom power]

2. they had plans, but they were all predicated on "no drought"

Of course, for anybody thinking in terms longer than a few decades, that's about as bad as no plan at all.

I'm sure that anybody who tried to bring up the inevitability of a 20 year drought was met with something like "LaLaLaLa, I'm not listening to you!". Or maybe "shut up, you anti-growth tree hugging marxist."

[NNadir]

4. I prefer "shut up, you anti-growth tree hugging marxist," but I like

formal forms of address. :-)

[ramapo]

3. Damn...incredible

Amazing, thought provoking pictures...

There's much info available regarding the silt buildup. Estimates range from 100 to 750 years until the dam is done.

Do a google on Lake Powell siltation and you'll be busy reading for some time.

The massive population buildup in the Southwest has to be one of the dumbest moves in history. But I guess hubris conquers common sense.

Not only do millions of people move to the desert but they want private swimming pools, green lawns, and an artificial environment that is 30-40 degress cooler than the natural temperature.

Sooner or later Mother Nature gets the last laugh.

[hatrack]

5. My personal short & sweet favorite: Nature Bats Last

.

[phantom power]

6. Or: "The economy is a wholly-owned subsidiary of the environment"

[hatrack]

7. Related - "Elephant Butte Res. (NM) Could Be A River In AYear"

TRUTH OR CONSEQUENCES— "If the regionwide drought holds true to form, the prospects for Elephant Butte Reservoir next summer look grim, according to the Bureau of Reclamation.

The federal agency presented a sobering forecast to residents here Thursday evening.

Spring runoff that was only about 11 percent of normal this year and an interstate water delivery deal with Texas that allowed New Mexico to store more Rio Grande water upstream left Elephant Butte Reservoir with only 147,900 acre-feet of water— about 7.5 percent of capacity— by mid-September when the gates at Elephant Butte Dam were closed.

The stark reality is that, even if spring runoff from the southern Colorado snowpack that feeds the Rio Grande is close to 100 percent of normal— a level not reached in seven of the last eight years— the reservoir is still expected to drop an additional 15 feet below this year's low point after southern New Mexico, Texas and Mexican farmers are given their irrigation water allocations, said Bureau of Reclamation hydraulic engineer Wayne Treers."

EDIT

http://www.abqjournal.com/water/104476nm10-31-03.htm

This news article was from Halloween 2003. The current situation is that the most recent data available shows that Elephant Butte, with a capacity of about 2.1 million acre-feet, held (as of 26 July 2004), 143,740 acre-feet - that is, 6.8% of capacity.

http://www.usbr.gov/uc/elpaso/water/Reservoirs/ElephantButte/Storage.html

[hatrack]

8. Also related - silt delta front now well past Hite on Lake Powell

EDIT

"The Colorado River is one of the most sediment-laden streams in North America," Dohrenwend said. "Deltas on the Colorado River, coming into Lake Powell on the north, and on the San Juan River, coming into Lake Powell on the southeast, are today more than 30 miles long, and advance at an average rate of about a mile a year."

During the past 35 to 40 years, sediment at the confluence of the Colorado and Dirty Devil rivers, just upstream from Hite Marina and the present delta front, has grown to about 185 feet thick. Sediments from the recently exposed delta have been eroding at a very rapid rate, Dohrenwend observed. "In the past several months, the delta front has advanced almost a mile and a half," he said.

EDIT

The important issue, beyond the immediate fate of Hite Marina, is "where does all of this sediment go when it reaches the lake?" Dohrenwend said. Scientists and engineers realized 60 years ago that when a sediment-laden river enters a reservoir, the river water deposits much of its sediment at the upstream end, but also creates a 'density' current that flows along the bottom of the reservoir, dumping sediments all the way along to the face of the dam. "There is significant sedimentation at the Glen Canyon dam face even now," Dohrenwend said. Added to that, the Colorado River is a desert river with a volume that fluctuates widely, so the reservoir volumes also fluctuate widely, and that further complicates how sediments are deposited behind the dams, he said.

EDIT

"My point is, who is studying this?" Dohrenwend said. "It's a time-sensitive problem that needs to be studied. We need to study it, if only to learn more about how sediment will be deposited in major reservoirs so that we can more accurately forecast the useful life of these reservoirs. Or perhaps we might develop some ideas of what we might do, or what future generations might do, when it's time to decommission these things."

EDIT/END

http://uanews.org/cgi-bin/WebObjects/UANews.woa/wa/MainStoryDetails?ArticleID=7290

At the time of publication the delta front had moved abot 1.5 miles downstream in a couple of months. That was in spring, 2003. Now (August 2004), the water level is another 35 feet lower than when Dohrenwend wrote this article.

Sedimentation is about as unsexy a problem as I can imagine, but in large measure it (along with drought) is going to define life in the coming century for millions of Americans living west of the 100th meridian.

[redqueen]

9. Do you know if any of the universities in the area are studying it?

If not, perhaps some of us should start suggesting it...

[phantom power]

10. Glenn Canyon Institute

http://www.glencanyon.org/

On a related topic, there is a yearly bill that somehow gets passed in Congress that *forbids* any federal funding being spend on an environmental impact statement for decomissioning Glenn Canyon Dam.

It's sponsored by some southwest congressman every year. It's ridiculous. They forbid spending money even to study the problem.

[hatrack]

11. I know that Reclamation has an office of sedimentation . . .

Beyond that, I'd hazard a guess on the University of Arizona (judging by one of my prior posts above), and maybe the Colorado School of Mines, though they tend to focus somewhat more on applied engineering.

[pmbryant]

12. Fascinating

Any pictures of what this area looked like pre-Dam?

--Peter

[hatrack]

13. A few samples, but you'd be better off with a book

Quite small, however - this is looking to the NE from the old ferry site.


Also small - an old Indian ruin looking off to the NW from just above the ferry.


This is one of the side canyons


Cathedral In The Desert - Note human figure at lower right for scale (not at Hite - much farther downstream in the Escalante drainage)

There's a book called "Peaceful Canyon, Golden River", which has really excellent photos on its pages, and includes a whole CD-ROM with hundreds more.

[phantom power]

14. There's a gallery here

http://www.glencanyon.org/pictures/pictures.htm