Lake Mead NV speedboat (#0116)

It's a water intake from the lake. IIRC it now belongs to the Southern Nevada Water Authority and so provides water for all of southern Nevada, not just Vegas. Since it's about to be left high and dry, the SNWA has been building a new intake, a tunnel out under the lake, at a cost of ~$1 bill. It was just opened: here's a link:
www.cbsnews.com/news/las-vegas-uncaps-lake-meads-third-straw-for-water-supply

Back In The Day a good buddy of mine who had a boat on Lake Mead (well, truth to tell, it was his mom's boat) thought it was great fun to drive unsuspecting passengers under that water intake. It leaked enough that they'd get seriously splashed! Of course, that's not possible now--

The intake is built on the side of Saddle Island, which is an island only at the very highest water levels. It's actually an outcrop of Precambrian crystalline rock, unlike the much younger volcanics in the mountains around.

Yep. It was a WW II crash project, magnesium being critical to the then cutting-edge technology of aircraft construction. The mine at Gabbs in central NV was opened and the MgO ore shipped circuitously by (mostly) rail up to Reno, over to Salt Lake, and then down to Vegas, where it used the spur that had been built for Hoover Dam's construction. The plant was located there because the electrolytic process for Mg extraction uses enormous amounts of electricity, and Hoover Dam had just come online--

Thanks for this detail, very helpful. I need to search around for a map of historic rail lines in Nevada -- from the satellite view it looks like there's the remains of a roadbed west of Gabbs.

The rail line came down to Luning from the north, thru Hawthorne, right along US 95. Till recently there were still old loading chutes on the north side of Luning, but IIRC they were finally torn down in the last few years. The ore came to Luning by truck--that was the only non-rail leg. The railroad still runs as far as Hawthorne, because of the military traffic, but the tracks farther south were ripped up (again IIRC) in the early '90s (that late!) The ore then went north to pick up the transcontinental line near Fallon and thence over to Salt Lake. There'd once been a rail line from Vegas thru Beatty up to Tonopah, dating from the early 20th century, but it was ripped up in the late '20s. The eccentric who built Scotty's Castle bought lots of the ties, and you can still see them stacked on the grounds. Here and there, particularly around Lathrop Wells and southward, you can still see the old R/W from off US 95.