Orestimba Creek Feasibility Study - Stanislaus County

Economics Appendix – Draft Report - Orestimba Creek Feasibility Study, Stanislaus County, California – September 2012
Orestimba Creek floodwaters eroded the west embankment of the Anderson Road bridge causing
it to drop 2 feet in elevation and create several cracks in the bridge.
In early February 1963, about 6 inches of rainfall over the Orestimba Creek basin caused both
flooding and one of the largest peak flows of record. About 2,000 acres located 4 to 5 miles
north of Newman were inundated by shallow floodwaters. Agricultural lands experienced soil
erosion and silt deposition. The DMC siphon and access ramps to both road and railroad bridges
were eroded to an extent that required repair. These floodwaters left debris that had to be
removed.
Extensive rainfall in January 1969 caused the flooding of nearly 2,000 acres. Flood damages
occurred primarily on agricultural lands and consisted of erosion of agricultural soils, deposition
of sediment, and prolonged field inundation which adversely affected area walnut orchards.
In March 1995, Newman experienced the worst flood in the city's 107 year history. During the
storm, the valley floor received between 2.5 and 4.0 inches of rain within 24-hours and more
intense rainfall in the foothills. On March 10, 1995, the USGS gauging station located upstream
from the California Aqueduct siphon registered a peak flow of 12,000 cfs. A convalescent
hospital located on the north side of the city was entirely inundated by 2 feet of water in the
building and 4 feet of water in the parking lot. Sixty-five residents were evacuated by a Medi-
Flight helicopter after a failed attempt to use two ambulances and a school bus. Expansive areas
of agricultural cropland were inundated by floodwaters. Additionally, a bean crop storage
facility located just north of the city experienced extensive flooding affecting land and property
forced the business into bankruptcy shortly after the flood. A neighboring agricultural packing
facility also experienced flooding.
During the 1995 flood event, many public streets and highways, including State Highway 33,
were closed. These road closures limited or, in some cases, prevented access for emergency
vehicles which resulted in diminished local and regional emergency response capabilities.
Similar public health risks caused by area flooding included floodwater affected domestic water
wells and individual septic systems, many of which were rendered unusable.
In 1995, the city of Newman incurred reported flood damages of $7.8 million dollars (2011
prices). Additionally, a bean crop storage facility located just north of the city experienced
extensive flooding affecting land and property that loss of $465,000 dollars and was forced the
business into bankruptcy shortly after the flood. This facility closure resulted in lost wages and
income for 14 employees and 20 to 25 local growers. Another agricultural packing facility
experienced $400,000 dollars in losses. Many public streets and highways including State
Highway 33 were closed that limited or prevented access for emergency vehicles resulting in
diminished emergency response capabilities. Flooding that affected domestic water wells and
septic systems rendering many unusable also increased public health risks.
Actual damages incurred from the 1998 flood are not known.
The actual monetary cost of flood damages incurred by private property owners in West
Stanislaus County during the most recent floods of record are difficult to fully assess. There are
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