The roots of the federal government's role in providing flood control and combating soil erosion trace back to the Civil War, but its function and process have evolved dramatically in the many years that followed. In 1862, President Abraham Lincoln established the U.S. Department of Agriculture (USDA) to acquire and diffuse useful information about agriculture. Twenty-eight years later, the USDA began the practice of agricultural engineering to irrigate crops. In 1902, drainage investigations became an added responsibility. In 1933, the Soil Erosion Service (SES) was established within the Department of Interior to combat the "national menace" of soil erosion. During the peak of the dust bowl in 1935, after a dust storm from the Great Plains moved over Washington, D.C., Congress passed the Soil Conservation Act, which formed the agency now known as the Soil Conservation Service (SCS). The SES subsequently was merged into the SCS under the USDA.
Recognizing that floods originate in the headwaters of a watershed, Congress passed the Flood Control Act of 1936, which designated the USDA to conduct investigations of watersheds and implement measures to retard soil erosion and stormwater runoff. It permitted the federal government to participate in improving the watershed and tributaries of navigable waterways for flood control purposes if the benefits of the project were greater than the estimated cost. From 1936 through 1941, the Flood Control Act was amended to authorize the USDA to investigate additional watersheds. By these amendments, the USDA was now authorized to investigate watersheds in three-quarters of the United States.
Early watershed improvements carried out by the USDA involved land treatment measures to restore vegetation, improving infiltration and water storage within the soils. Beginning in the late 1940s, structural measures, such as floodwater-retarding structures, sediment-control structures, and channel stabilization, were conceived to hinder erosion and control flooding.
The Sandstone Creek Watershed, located on the Washita River in south-central Oklahoma, is the site of the world's first, completed upstream flood-control project. The project comprises 24 dams, which control runoff from 70 percent of the 107-square-mile watershed, and protects 90 percent of the floodplain. Construction of the structures began in June 1950 and was completed about two years later.
The USDA Appropriations Act for fiscal year 1951 established funding for implementation of the structural measures identified in 11 watersheds previously studied under the Flood Control Act. Under the pilot program, dams were constructed in the following watersheds:
- Los Angeles River Basin, Calif.;
- Santa Ynez River Watershed, Calif.;
- Trinity River Basin, Texas;
- Little Tallahatchie River Watershed, Miss.;
- Yazoo River Watershed, Miss.;
- Coosa River Watershed, Ga. and Tenn.;
- Little Sioux River Watershed, Iowa and Minn.;
- Potomac River Watershed, Va., W.V., Md., and Pa.;
- Buffalo Creek Watershed, N.Y.;
- Colorado River Watershed, Texas; and
- Washita River Watershed, Okla. and Texas.
The Watershed Protection and Flood Prevention Act was enacted in 1954 and charged the USDA with creation of a permanent nationwide program for upstream watershed protection and flood control. The program was established such that the USDA provides technical and financial resources to local watershed groups, but is a federally assisted program, not a federal program. Projects were limited in size to a maximum watershed size of 250,000 acres and maximum storage capacity of 5,000 acre-feet. Under this program and its predecessors, approximately 11,000 flood-control dam projects were constructed by the SCS in 2,000 watersheds located throughout 47 states, since 1948. The following table identifies each participating state and the number of dams constructed.
Table: Constructed SCS flood control dams, by state