Mechanically-Made Beaver Dam, "Mississippi River Basin"1944-08-01unknownhttp://rightsstatements.org/vocab/NKC/1.0/enghttp://congressarchives.org/record/CAC_CC_053_4_0000_1_126Blueprint/Hydrological Map by Steen: This blueprint illustrates the typical locations of upstream check-dams for erosion and flood control, but it does not depict the complete drainage area of all lakes and streams, as noted in the annotation. Dimensions: Not specified.