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.
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
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