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Dickinson Unit
Photo of Dickinson Dam and E.A. Patterson Lake
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Pick Sloan Missouri Basin Program
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Dickinson Unit History (38 KB) (pdf)
General Description| Plan| Development| Benefits
General Description

Dickinson Dam and Reservoir (Edward Arthur Patterson Lake) store water for irrigating valley lands downstream from the dam, and for a municipal water supply for the city of Dickinson, North Dakota. Some 400 acres of irrigable lands, in isolated tracts, are served by privately constructed pumping plants located along the Heart River near Dickinson. Flood control, fish and wildlife, and recreation benefits also are realized.

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The water supplied from Edward Arthur Patterson Lake is pumped by private operators; therefore, the Federal Government does not contemplate the construction or operation of irrigation distribution works.

Facility Descriptions
Dickinson Dam

Dickinson Dam is a homogeneous earthfill structure across the Heart River, 1.5 miles west of Dickinson, North Dakota. The dam has a structural height of 65 feet, is 2,275 feet long across the crest, and contains 324,000 cubic yards of materials. A combined overflow spillway and outlet works is located near the right abutment of the dam. In 1981, a spillway gate was added, and conservation storage was increased. This increased the available water supply for the city of Dickinson. The capacity of the spillway is now 38,800 cubic feet per second at a water surface elevation of 2430.6 ft, and the outlet works now has a capacity of 45 cubic feet per second at a water surface elevation of 2420.0 ft. An auxiliary grass-lined spillway was also completed in 1981 to pass a revised inflow design flood.

Operating Agencies

Dickinson Dam and Edward Arthur Patterson Lake are operated by the Bureau of Reclamation.

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Settlement of the area began after 1864. The early occupants were ranchers who settled along the streams and used the public domain for grazing large herds of livestock. With the building of the Northern Pacific Railway into the Heart River Basin in the 1880`s, immigration became general and large ranches soon gave way to homesteads. Large numbers of settlers came during 1900-1910, and engaged in the production of cash grain farming and as a result extensive areas of rangeland were plowed up and the remaining range was grazed intensively. Although livestock production continued to be important, the increased demand for wheat during World War I brought on a tremendous expansion in wheat acreage. The drought years of the 1930`s and prevailing low prices seriously disrupted the economy and led to emigration and abandonment of farms.


The Reclamation Service first recognized the potentialities of the Heart River Basin by making a reconnaissance survey of the area in 1903-1904. The comparatively high cost of developing the basin and lack of active support from the landowners led to the conclusion that further studies were not justified. The demand for irrigation and flood control increased and decreased with the climatic cycles.

The Bureau of Reclamation began new investigations in 1926. The study showed that land could be irrigated and floods controlled, but no further work was recommended. The Corps of Engineers conducted surveys and issued reports in 1934 and 1937, and in 1942 the Bureau of Reclamation completed an investigation of the Heart River Basin and proposed the Heart Butte and Dickinson Units for development.


The Flood Control Act of December 22, 1944, Public Law 534, which approved the general comprehensive plan set forth in Senate Document 191, as revised and coordinated by the Senate Document 247, 78th Congress, 2d session, authorized the unit.


Construction of Dickinson Dam began in March 1949 and was completed in March 1950. Initial water deliveries were made to the city of Dickinson in May 1952.

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Storage of floodwater has transformed 400 acres of irrigable lands from uncertain dry-farming to production of alfalfa, oats, corn, barley, potatoes, and truck crops.

Municipal and Industrial

The storage of water has enabled the city of Dickinson to maintain a water supply for municipal and industrial use.


Edward Arthur Patterson Lake is located in the prairie uplands where there are no natural lakes. Although small, it has provided new types of recreation for south-western North Dakota and is highly popular for camping, picnicking, swimming, boating, and fishing. The Dickinson City Park Board administers the reservoir area for recreational uses.

For specific information on recreational opportunities at Dickinson Dam click on the name below.

Dickinson Reservoir

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Last updated: Apr 04, 2013