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The Flood of March 1940 on the Sacramento River System


The Flood of March 1940 on the Sacramento River System of Northern California was distinguished by numerous levee breaks along both sides of the Sacramento River. Flood levels were near record along both the Sacramento and Feather Rivers; had the numerous breaks not occurred, flood levels would have been even higher. Levees all along the system were severely tested where they did not actually fail. Vast tracts of agricultural land were inundated, as were many farmsteads and a number of small towns, notably Meridian, on the east side of the Sacramento River near the Sutter Buttes, between Colusa and Yuba City. Highways, bridges, and railroads were damaged, washed out, or overflowed throughout the Central Valley.


A major flood control dam and reservoir on the Feather River was a distant engineering dream (realized in the 1960's in Oroville Dam, a component of the California State Water Project.) Shasta Dam, the keystone facility of the Central Valley Project on the upper Sacramento River, was under construction by the U.S. Bureau of Reclamation. 


The Sacramento River Flood Control Project in 1940 consisted of levees - some privately built and maintained - of varying quality, age, and capacity; aided by a series of relief weirs and bypass channels. With one exception these weirs are "fixed weirs", essentially low dams in the levees that permit the swollen river to spill over the side and release excess flood flows into basins and wide "bypass" channels set aside for that purpose. Only one of these weirs has a control structure in the form of gates which can be opened (but not closed again until the water level recedes): Sacramento Weir, located near the City of Sacramento near the confluence of the Sacramento and American Rivers.


This system of levees and bypasses was originally designed based on flood data from the floods of 1907 and earlier, and had been tested by only one outstanding flood event in 1937. The Flood of 1940 was a major test and wake-up call for flood control agencies, engineers and residents of the historically flood prone Great Central Valley of California.


The photos here were originally taken by employees of the U.S. Bureau of Reclamation. Several years ago an attempt was made to locate the negatives without success. The images were scanned from prints in the MBK Engineers collection, and in some cases cropped and digitally edited for clarity and brightness, for use in digital video display form here.



1940 Colusa Flood Aerial

Flood of March 1940. Aerial photo looking east toward the Sutter Buttes, the town of Colusa on the Sacramento River in the right foreground.    The great Sutter Basin, a natural overflow area incorporated into the flood control project as a bypass, is filled entirely, stretching from the Sacramento River east levee to the foot of the Sutter Buttes (the miniature mountain range in the distance.) Water enters the Basin through overbank flow along the east bank of the upper Sacramento River, and through two of the fixed weirs, Moulton Weir and Colusa Weir (just upstream, to the left of this photo). The Sutter Basin empties into the Sutter Bypass, a wide flood channel that carries excess Sacramento River flood water parallel to the River down to the confluence of the Feather and Sacramento Rivers.


The town of Meridian, flooded in 1940 from a levee break along the Sutter Bypass, is just to the right of the photo in the distance; Colusa Bridge can be seen across the Sacramento River in the near right of the photo. Both sites are shown in other photos below. (Still under construction...)


 SR-173-CV B.D. Glaha, U.S.B.R March 1940

1940 Flood Aerial


Flood of February-March 1940. The Sacramento River at the City of Sacramento, looking upstream toward the I Street Bridge.  A remnant of times past, a steamboat in daily service on the river is moored at wharves along Front Street. Taken from the M Street Bridge (the "Tower Bridge"), with the river near crest stage.

SR-188-CV H. R. Whaley, U.S.B.R Feb. 28, 1940


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