Friday, May 7, 2010

GC dams: Clearing Ground --and Digging It Out

The rush on the Federal Power Commission in the 1920's was speculative fever. The multiplying applications were spun from the not unusual conviction that wealth was to be had, and without much work. Girand's Diamond Creek project, perhaps seeming the most solid, only drives the point home, as is indicated in the comment Boyer and Webb extract from the 1923 USGS survey narratives; Stabler, one of the topographers, says that Girand had picked the best site for a low dam, but it was scarcely suitable for one to more fully utilize the potential by reaching back to Havasu. He himself speculated on a couple of other nearby sites, and then as the survey proceeded, they came upon a "remarkably fine" site with "great opposing granite walls". Which of course, had not even been taken up during the rush; it was not known. It would be, for this was the Bridge Canyon location.
(Yes, Killroy was here at Bridge, too. Photo by Duwain Whitis, Jan 2010, courtesy of Tom Martin of River Runners for Wilderness.
Certainly a "remarkably fine" undamsite. Cf. entry of 11 Apr 2010)

Just as the Girand story had been getting underway, E. C. La Rue wrote for the USGS in 1916 a compendium monograph on "The Colorado River and Its Utilization". What it mostly revealed was the scarcity of data. Its discussion of damsites (except for one near the Green-Grand junction) was cursory, and not informed by the kind of work the 1923 survey did in the Grand Canyon. In effect, La Rue laid the foundation for thinking in an informed way about irrigation, primarily along the lower river, and tied it into the need for storage and flood control. That was the big Colorado River news in the first 20 years of the twentieth century, and La Rue's work played into the focus on California. That he then developed ideas that tried to shift that focus only resulted later in his own frustration and career decline. While the work done by the 1923 survey was fundamental and the best done on the river so far only intensified the irony of its being irrelevant.

As Girand pursued his plans, as the USGS professionalized knowledge about the river, California (specifically Los Angeles), with its dramatic lower river floods, its imperious grab for irrigation and drinking water, and its growing enchantment with electricity, bulled ahead. The Reclamation Service's chief, Arthur Davis, was convinced, perhaps as early as 1919, certainly by 1922, and had convinced the Interior Department, of California's priority. Six Basin states went along and made a Compact; Arizona emphatically did not. No matter, and no matter too as regards the FPC and Girand's scheme, stalled then junked. 

The physical embodiment of that priority was, of course, the Boulder project of building the high, large-storage, Hoover dam in Black Canyon. Floods would be detained, kept out of California-- incidentally evaporating lots of water, just as La Rue had feared.* Irrigation and city water could then be released to be diverted as needed. Power would be generated, and the lines would head primarily west. The 1920's came to a close with California's victory; the Depression closed in, the dam went up. And for a time, the Grand Canyon was left to its own devices. In a few years, this would change. The Colorado would begin filling Hoover's reservoir, and as well silt up the lower 40 miles of the Grand Canyon, a quiet encroachment that was intended as the signal for much greater damage to come. Oh, excuse me, I should have written "benefits".

Here's some of that silt, mile 266. Photo by Miles O'Kelly from Jan 2010, again courtesy of Tom Martin, RRFW. The cable of the tramway used to export bat guano up to the rim (a story for another time) is sticking out; above it, Tom says, the deposit is more clayey; the lower part has more river sand. How much longer until the river has excavated all the way through to bed rock?
Which reminds me that I just went through an article by USGS scientists T.C.Hanks and R.H.Webb, "Effects of tributary debris on the longitudinal profile of the Colorado River in Grand Canyon", Jnl. of Geophysical Research: VOL. 111, F02020, doi:10.1029/2004JF000257, 2006.  If I understand it correctly, the article portrays a changing river regime over recent geologic time, with a river powered by huge flows from glacial melt cutting down through bedrock layers (to a depth below that of the present), followed by today's "anomalous and transient" period of aggradation, giving us our pools and rapids. The implication is that those silt banks dont stand a chance -- in geologic time, anyway.

* P.s. Powell thought deeply and well about our arid West. La Rue brought passion and skill to his technical delineation of the Colorado. No matter; they got stomped by the boomers & boosters, who always prefer fantasy (where is Hollywood, after all?) to informed thought qualified by the physical realities.

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