In the factual heart of his 1925 monograph, La Rue poured out his expertise, describing each of the damsites, giving location along the river and in the geology, including usable materials. He had photographed each site. He offers ideas on spillway and powerhouse location. Plan-view maps fix the ideas. He discusses water supply and power capacity. always in horsepower (When did the kilowatt come into use? Although I am not providing any numbers, 1 hp ~ 3/4 kw.) He proposed needed transport. In conclusion, he fits each site in his overall scheme.
To start, his proposed Redwall site is just up from the Fence Fault at river mile (rm) 30. No spillway, and the water would have to go 1000' through tunnels to the power plant. The crest would be at 3108' elev., a modest 222' high. It was engineered so as not to interfere with his Lee's Ferry site. He offers an alternate site a couple of miles downstream, later surveyed hard by Reclamation. La Rue, however, found no favorable place there for the powerhouse or construction camp.
After rejecting all further locations --on account of unfavorable rock-- above the first Granite Gorge, he selected Mineral Canyon, a mile below Hance Rapid. To get full advantage of this site at would require a 345' dam at rm 78, thus using for reservoir storage what was no good for dam foundations. Again, it would be an overflow type. He re-emphasizes how the storage and control at his Lee's site would provide for full use. He does not bring up the silting in from the Little Colorado, a little surprising given the massive flood he experienced during the 1923 trip. Nor does he see a problem with evaporation due to how the Grand Canyon broadens. Access to Mineral Canyon would be a matter of extending the railroad along the rim for 12 miles, with an inclined railroad down to the river. Or if in the future, several dams are to be built, each lower site reservoir could ease the way to the next above.
In the next 100+ miles, the river falls 1000 feet. He analyzed nine sites down to Havasu, a power development "for the distant future", finding its market in the southern parts of California & Arizona. In discussing how he chose his three preferred sites, he eliminates one because it would be 400' high, an "unprecedented height" -- yet Hoover would be completed at over 700' in ten years. He did prefer moderation, and must have been exasperated by the hubristic water waste from Mead reservoir. The sites he favored were Ruby Canyon, Specter Chasm, and Havasu, rm 104, 130, and 156.
Water from Ruby would go up to 2521' elev. The loss of the suspension bridge would be alright since a motor-driven ferry could do the job, and Phantom Ranch would be safe, by 30'. Remembering that he did not like river travel, he notes that the inner gorge would be accessible to all, avoiding the "hazardous undertaking" of running the "dangerous rapids". However, the easy access did not mean that he was advocating such dam construction in the National Park, just calling attention to the power potential.
Once west of the Park, and following his course of making a comprehensive plan, La Rue list the priorities as flood control, water for cities, irrigation, and then power, all under the prime claim to conserve water. He condemns the "haphazard policy" so far followed for development. Thus projects have been built or planned without regard "for the full utilization of the water resources". He lists 23 sites from Havasu to Parker in 368 miles, including two not previously considered that are "admirably adapted" for optimum use. He then again lays out the debate: First, the California-leaning plan for one high dam near Boulder Canyon, "a scheme…never been tried" for flood control, irrigation, silt storage, and power. Opposed to this, his plan for major regulation above the Grand Canyon, with a secondary structure in Movhave Canyon below Boulder, and the canyon sections "left free" for power dams. He does include a high Bridge Canyon dam to show the power value below the National Park, but pretends to prefer lower dams. Unless. And here comes his curve, unless Bridge is a diversion point for a gravity supply to irrigate in Arizona or to supply California cities. His "moderate" dams are "well within the limits set by modern engineering practice", as compared to the "unprecedented" high dam at Boulder.
A reflection is in order here on the proportions involved in this debate of the proper scope for a plan, dreams of pushing the boundary of "engineering practice", political weight, and ego. Both sides (actually there were other schemers & boosters, too) mix in the technical and the romantic, calculated need and desire for power (the non-electrical kind). That California seems in retrospect the easy winner should not blind us to the passion and fact-based convictions that for over ten years moved all the players. Although the Hoover story is very peripheral to my Grand Canyon stories, La Rue was representative of those who looked at the Canyon and saw development, progress, a better, electrified, life for the Southwest. Politics may seem to be decisive, but if so, La Rue stands out (as did the Powell of "Arid Lands") as a visionary for intensive human use of the planet.
La Rue continued his plan with power dams that stepped up the Colorado to the Park's west boundary, of which Devils Slide and Bridge were completely within the Canyon, while the Hualapai Rapids site would back water past Pierces Ferry some 20+ miles. He emphasized the water saved under his plan, and thus the more acres irrigated and power generated. In presenting his plan, he now ignored Diamond Creek and the Girand-FPC arena, concentrating first on his "discovery" of the Bridge Canyon site at rm 235-6. (He noted that as of the 1923 survey, nothing was known about sites below Diamond Creek.) Hard rock, the deepest part of the narrow gorge, abundant construction material on-site--a dam could be up to 800' (oops, what about "engineering practice"?)--; he settled for 566', to get the water upstream to the Havasu site (and the silt up to…, but he doesnt deal with that). The power house would be close as would the construction camp, and the first 18 miles of railroad from the Santa Fe mainline could be constructed at "minimum cost", and with a tunnel, the rest would be easier than one down Diamond Creek. In passing, he opined, "There are no important improvements in this part of the Grand Canyon. The flowage damage would therefore be negligible."
Carried away by this near-perfect site, he provided a further apple: Build the dam to 825' ("practice" makes hubris?), then a 72-mile tunnel to carry water by gravity to Topock and across the Colorado to California's cities. So much power could be generated from such a dam as to pay for itself. So it "has merit". Oh, and it would back water to the Specter site in the Park, making, no doubt, the next step upstream easier to build. That idea could also be used for the Devils Slide structure, ~rm 255, working upstream from another dam at Hualapai Rapids.
Going on to alternate sites, La Rue casts doubt on a site at Prospect Canyon, and then on Girand's and other Diamond Creek locations, all inferior to his Bridge site. He briefly describes, only to dismiss, Travertine, Spencer, Flour Sack, Pierce Ferry, and Grand Wash. The monograph peters out as he continues downstream-- his survey comprehensive, but his heart was in his grand plan, set out and argued for many pages earlier.