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| Bill Neill | Trip Reports

2019 - Trip Report - Hansen Dam Basin Tour

Hansen Dam Basin Tour  Trip Report and Photos:
Bill Neill

A Sunday morning tour of Big Tujunga Wash and Hansen Dam flood control basin, at the northeast corner of San Fernando Valley, was lightly attended, probably because I could not obtain permission for a 4WD caravan. But because our party of four could ride in one vehicle – my Toyota 4Runner, with entry authorization –
we were able to drive across the basin by vehicle after a short hike on equestrian trails.

My vehicle was authorized because I have worked in the basin on invasive weed control for the past three years, as a contractor to the Los Angeles Conservation Corps and National Forest Foundation. Other participants on the Sunday tour were Jay Lawrence, Craig Baker, and my non-DE guest Carvel Bass. Jay was interested in the area because his grandmother’s uncle, Homer Hansen, owned the property before expropriation by the Army Corps of Engineers in the early 1940’s. Craig was interested because he lives nearby; and I invited Carvel because he was involved with resource management for 25 years as an ecologist with the Army Corps of Engineers.

Our hiking tour included several shallow-water crossings, which we managed to cross without getting wet. Our target for historical exploration was a massive concrete structure about 300 feet long on the south edge of Big Tujunga Wash. Based on its length and funnel-like openings on top, we concluded that the structure was a gravel hopper for loading rail cars. Our discovery on one portal of a 1923 California license plate impression confirmed my theory that the structure dated from the economic boom period of the 1920’s. If the hopper structure was accessed by trains of rail cars as we concluded, then steel rails must have been removed during World War II or before, because we saw no sign of rails or ties currently.

Our hike on equestrian trails was impeded by fallen dead trees burned by a large wildfire two years ago. I had hoped to have these trails cleared by a LACC chainsaw crew during late October, but business arrangements were not finalized by then; so to prep for the tour, I had cut some of the obstacles manually using my bow saw, and in other places we had to step over or duck under the recumbent dead trees.

Our vehicle tour stopped at a collection of stacked concrete slabs, whose history had been a mystery to me. According to Carvel, the slabs were derived from a Caltrans project following one of the earthquakes in San Fernando Valley, and the Army Corps of Engineers accepted the concrete slabs for storage with the idea that they might be useful for something. Recently about 25 slabs were taken by a fire department for construction of helicopter landing pads, but a sizable number remain.

One day after our tour, Craig Baker sent a link to the website “Historical Aerials”,, which displays old aerial photographs and topographic maps as old as 1900. For the Hansen Dam area, the oldest aerial photo on the website is from 1952, postdating the dam construction; but the 1926 and 1932 topo maps show a rail line reaching the gravel hopper area from the southwest. Then Craig realized that a segment of the rail line still exists today, providing access to the “Valley Steam Plant”, an electrical power generating station operated by Los Angeles Dept. of Water & Power, where Craig was employed during his career as an electrical engineer. 

So here is the answer to a historical trivia question: If you ever wondered why the LADWP power plant in San Fernando Valley is located where it is, the answer is that the power plant is located next to a short rail spur that originally extended another two miles to the northeast, to a concrete gravel hopper of 1920’s vintage on the edge of Big Tujunga Wash.  ~ Bill