By the time of the Army Corp report conducted its inventory most of the North Fork Ditch had been lined with concrete. Many of the appurtenances were also concrete such as wasteways, intake structures and sluice gates. Of the 37 flumes, 32 were constructed of timber and only 5 were metal. The timber flume construction allowed them to be built with small changes or bends in the direction to navigate around boulders and hillsides. The metal flumes, by contrast, were best adapted to spanning a small ravine in a straight line.
Within the rate submission was a detailed outline of the Natomas water canal along with photos of the Natomas Dam on the South Fork of the American River, the New York Ravine wooden siphon, and other pictures detailing the canals and flumes. The detailed history of the Natomas canal ownership along with a complete inventory of the structures submitted with the application for higher water rates gives a glimpse of this important gold rush era water works project.
If you want to actually get to the base of the Birdsall Dam site, which was my goal, you have to be more adventurous. You must leave the Pioneer Express Trail and hike around the American River bottoms.