Titled "Characteristic Section of Brush Dams Built on the Yuba and Bear Rivers," the sheet is a detailed cross-section drawn to a scale of 5 feet to the inch, showing the layered brush, timber, and rock construction with its dimensions and slopes.

Like its companion map of the Bear River flooded lands, this plate accompanied the report of January 10, 1881 and is signed by G. H. Mendell, Lt. Col., Corps of Engineers. 

It was printed as a folding plate in House Executive Document No. 76, 3rd Session, 46th Congress.

The brush dams were part of the engineering effort to hold back the mining sediment that was burying Sacramento Valley farmland and choking the rivers — the same conflict that culminated in the landmark 1884 Sawyer Decision restricting hydraulic mining. 

Mendell, of the Army Corps of Engineers, authored a series of reports on the problem and later served as president of the federal California Debris Commission. A scarce technical document from a defining episode of California and Gold Rush history.

Condition: Please review the photos, which form part of the description. The printed drawing is clean and crisp. As a folding plate removed from the bound document, the left (binding) edge is torn and chipped with old tape and paper residue, there is light toning along the folds, and the lower corner is lightly curled/creased. A good, displayable example with the noted binding-edge damage. Approx. sheet size 18" x 8.6".