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.
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