The study was undertaken to plan for the proper development of water andrelated land resources of the Willamette Basin in Oregon. Appendix B, along with Appendices A and C, provides supporting data for the functional Appendices D through L. Climate is first discussed, including the climatic significance of geographical features such as the Pacific Ocean, the Columbia Gorge, and the Coast and Cascade Ranges, climatic elements (e.g. , temperature, precipitation, evaporation), and meteorological aspects of major storms--rain, wind, and snow. A description of water resources, their distribution, and their variation at different times are presented. These resources are described in terms of factors influencing the occurrence of water. Specifically reviewed here are surface waters, groundwater, the relationship between surface and groundwater, management programs, and water rights and legal restrictions. Lastly, the adequacy of hydrologic data is reviewed. Statistical and interpretive hydrologic data necessary for broadscale water resources planning are provided. Data assembled are those concerning climate, streamflow, lakes and glaciers, chemical-quality, sediment, stream temperature, and groundwater. Geologic and soils mapping are briefly discussed, and a list of references is provided.