Durgan Bridge — Downieville, CA - U.S. National Register of Historic Places on Waymarking.com

The following information from California State Parks Office of Historic Preservation files:

The Durgan Bridge was built in 1938 across the North Yuba River and is a rare surviving example of a one lane, rigid connected Pratt through truss span. It was designed by county engineer George Taylor to carry local traffic on Nevada Street over the North Yuba River and the single lane bridge continues to carry automobile traffic on its one lane (11 foot, 10 inch) roadway today.

The Durgan Bridge is a 140 foot long through Pratt truss bridge constructed of riveted steel I-beams, running north-south on Nevada Street. The portal struts are reinforced with riveted diagonal bracing of steel I-beams, and each vertical truss is reinforced at the top with diagonal bracing of riveted steel L-brackets. Top lateral bracing of steel L-brackets are located between the struts along the top chord. On each end of the bridge is a builder’s plate reading “Judson Pacific Co., San Francisco, 1938.” The bridge is supported on steel stringers, with a roadway deck of poured concrete. The bridge is supported by two rectangular piers of poured concrete, backed by concrete abutments. A four-foot concrete pedestrian walkway is located on the eastern side of the roadway. On either side of the roadway deck are guardrails of steel L- brackets supported by steel I-beams, with chain-link fence affixed to the inside of the guardrails. A water pipe runs along the lower chord on the western side of the bridge.

The 1937 Downieville Flood

In 1937, Downieville had a total of five bridges. The easternmost (and farthest upstream on the Downie River) was the Hospital Bridge, originally called the Downieville Steel Bridge (due to its status as the town’s first steel truss bridge) constructed in 1908. Next was the Hansen Bridge, a Pratt pony truss bridge completed in 1936. Third was a concrete arch bridge constructed by the State of California to carry traffic on Highway 49. Just downstream of the highway bridge was the Jersey Bridge, a wooden bridge constructed in 1875, and the Durgan Bridge, just downstream of where the Downie River met the Yuba, constructed in 1881. Aside from the highway bridge, all were constructed as single-lane bridges by the county government.

On December 10, 1937, major storms sent a torrent of water through Downieville via both rivers. Nearly ten years had passed since the last high water, and an enormous amount of debris was swept into the river by the storm. State highway crews, aware of the storm’s danger, stood by to clear debris from the bridges, but as the river rose to the point where the highway bridge’s arches were underwater, clearing debris became impossible. The storm passed mostly under the Hospital Bridge and damaged the footings of the Hansen Bridge. The Highway 49 concrete arch bridge, unlike the truss bridges, had several pillars that extended into the river, and once road crews could no longer reach the bridge, debris collected on the piers and blocked the passage of water through the arches. The temporary dam brought the water level high enough to send the river through the streets of Downieville, lifting homes from their foundations and sending them floating downstream. The highway bridge could not withstand the pressure of the water and debris for long, and collapsed after approximately 30 minutes. The catastrophic break-through of water and debris caused more damage to the buildings of Downieville, and utterly destroyed the two wooden bridges downstream from the highway bridge, the Jersey and Durgan Bridges.

When Sierra County officials selected designs to replace the Jersey and Durgan Bridge in 1938, county engineer George Taylor designed two steel truss bridges. Taylor also chose to repair the damaged Hansen Bridge and retain the Hospital Bridge, whose unfashionable steel trusses had survived the disastrous 1937 flood. By the end of 1938, the town of Downieville was again connected by its four traditional single-lane bridges, all of steel truss design. The California Division of Highways rerouted Highway 49 temporarily over the Jersey Bridge as a temporary expedient until a new highway bridge could be constructed to replace the fallen 1936 bridge. As of 2016, no replacement bridge has been constructed, and the temporary expedient of the Jersey Bridge still carries Highway 49 through the city.