American entry into World War II marked a pause in Arizona's effort to become the sole proprietor of a dam in the Grand Canyon. However, it accelerated Reclamation's effort at figuring out what its role was to be in Colorado River development now that the Boulder Project was in operation. One of the chief planners, E. B. Debler, was deeply involved in how to bring water to the Phoenix area. Jumping ahead a bit in order to provide orientation, here is a map that brings together old and new alternate routes, from Debler's July 1944 summary:
At this time, the single purpose was to bring in a couple of million acre-feet of water for irrigation. The slightly shadowed areas show the potential irrigable lands.
Two of the the three alternatives Debler considered involved the Canyon directly. The eastern orange route brought water from Marble Gorge to the Verde drainage. The western orange is the tunnel+canal running from Bridge Canyon dam. At its terminus, it would feed water into the blue route taking the water east, the route that would also be used if the choice were instead to take the water from behind Parker Dam after letting it flow through Hoover's generators. For that route, power to pump the water would still come from Bridge.
The northern orange line marks the tunnel route to carry water around the Park for the Kanab power project. Just as the decision had to be made whether to cut the amount of river going through Hoover, so the eastern Marble-Verde possibility would have meant losing power from Kanab and Bridge, too. The decision for maximum electricity seems obvious now, and it is possible that Debler was only summarizing all schemes in order to show how obvious. He did point out that the blue route would get water to central Arizona soonest, a point in line with an Aug 1940 view from a Phoenix group (including Girand) that the water situation was a serious, even desperate, drought. Needed was a state authority to build an aqueduct from Parker dam.
An Aug 1941 program for national defense led to Reclamation preliminary reports in September on Bridge Canyon damsites. At first, Debler said he could not find a suitable site, but a second investigation by three engineers found there were excellent abutment rocks, with possible drawbacks due to constricted space and lack of aggregate. The upper Gneiss site (see below), however, was fine, without interference by Hoover's reservoir. If built to 1772' elev., a dam would provide 2-½ million kwh for copper mines and Los Angeles. A dam with power plant on the north side would take four years to build. There would be silt benefits for Hoover. National defense meant priority for a dam, so Reclamation dispatched a drill team to the damsite, and contracted for a topographic map.
This USGS topo, with a contour interval of 100' is titled "Bridge Canyon", surveyed in 1926, produced 1930, reprinted 1947 with "State of Arizona, State Water Commissioner". It shows "Bridge Canyon Dam Site" in the upper right, downstream of Bridge and Gneiss Rapids. At mile 236.5, this was the one otherwise labelled the "upper Gneiss" site; it had been La Rue's choice.
Sep 1941, Reclamation asked SecInt Ickes to let its Power Division represent Interior interests on a dam at Bridge, including those of the Park and Indian services. In November, Ickes directed those three to confer. Reclamation concluded after meeting that NPS had no objections and the BIA was only being "facetious" in asking for royalties--Hualapai probably only want hunting, fishing, and boating rights. (Hardly. This was the time that the Hualapai were winning in the Supreme Court their decades-long struggle to secure rights to their reservation. Soon they would begin in earnest their continuing effort to make the reservation pay, an effort focussed on this dam for the next 40 years.)
Gathering information, Reclamation learned that LADWP had discussed building a dam with SoCalEdison, and even preferred an Arizona state dam. Indeed, LA's Scattergood was opposed to a federal dam, supposedly because of pique over how Hoover operations had been handled; he would not extend the city's power line to a federal Bridge. The FPC staff, too, favored a state dam, though that was all on hold.
Meanwhile, Reclamation was pushing, even talking of building a dam in four years. The day after Pearl Harbor, Reclamation requested a defense priority rating to allow it to build a dam. Still preliminary, a March 1942 survey looked at four sites, upper Gneiss and miles 238, 239, 240--which three would be in Mead's backwater, so they were ignored. A reservoir to 1772' would go to Havasu. Silt would degrade operation by 1985, but upstream dams could alleviate. The capacity would be 600 megawatts (mw), and output range from 3.8 to 4.5 billion kwh, which would decline as upper basin uses its water. (Hard not to notice that all this "hard" information is presented as "this, but maybe that, or even, not". Talk about speculative engineering.) Power (200 mw) could be used to pump water to central Arizona. Reclamation reported further on the power market (including war needs) in July 1942, and planned geologic field tests, to take samples for testing. It argued in August for a 63' height increase to gain smoother reservoir regulation and a large increase in power revenue. Havasu would not be damaged, since silt could be quickly removed, and Supai could be more easily reached. Thousands could visit, and only a tiny bit of the Park would be taken. This was in the context of continued cooperation and discussion with the Park Service, which I will bring up to date in the next entry.
Archival sources: Bureau of Reclamation, incl. Phoenix and Boulder City offices
National Park Service
Federal Power Commission
Los Angeles Dept of Water and Power