In Jul. 1955, the U.S. Department of Agriculture (USDA) and the U.S. Forest Service (USFS) sprayed DDT as part of a Western spruce budworm control project in the Powder River control unit in Baker County Oregon.

Between 1945 and 1965, 1.82 million hectares, or about 17 percent of the total commercial forestland in Oregon, were treated with 2.02 million kg DDT. Although DDT residues were found at every point sampled, the levels of these residues were generally low.

Low levels in the surface mineral soils of both sets of transects further substantiate the fact that DDT is not readily leached into forest soils.