This study compares information on the Columbia River Estuary from a time predating most human impacts with corresponding information derived from recent sources. Section 2, Methods and Materials, describes the selection and use of materials to achieve this comparison. Surveys conducted from 1868 to 1873 are the source of the historical materials selected. These materials permitted the mapping and measuring (in acres) of five estuarine "habitat types": deep water, medium depth water, shallows and flats, marshes, and swamps. Also, the areas removed from the estuarine system since the 1868-73 surveys were classified into five additional categories according to current use. Separate maps of seven subareas were constructed to permit a more detailed analysis of changes in acreage. Each subarea was mapped twice, one for the past, the other for the present.
Organization