This document describes the U.S. Department of Energy's (DOE) Hanford Site environment. It is updated each year and is intended to provide a consistent description of the Hanford Site environment for the many National Environmental Policy Act (NEPA) documents being prepared by DOE contractors. No statements of significance or environmental consequences are provided. This year's report is the thirteenth revision of the original document published in 1988 and is (until replaced by the fourteenth revision) the only version that is relevant for use in the preparation of Hanford NEPA, State Environmental Policy Act (SEPA), and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) documents. The two chapters included in this document (Chapters 4 and 6) are numbered to correspond to the chapters where such information is typically presented in environmental impact statements (EISs) and other Hanford Site NEPA or CERCLA documentation. Chapter 4.0 (Affected Environment) describes Hanford Site climate and meteorology, geology, hydrology, ecology, cultural, archaeological, and historical resources, socioeconomics, occupational safety, and noise. Sources for extensive tabular data related to these topics are provided in the chapter. Most subjects are divided into a general description of the characteristics of the Hanford Site, followed by site-specific information, where available, of the 100, 200, 300, and other areas. This division allows the reader to go directly to those sections of particular interest. When specific information on each of these separate areas is not complete or available, the general Hanford Site description should be used. Chapter 6.0 (Statutory and Regulatory Requirements) describes federal and state laws and regulations, DOE directives and permits, and presidential executive orders that are applicable to the NEPA documents prepared for Hanford Site activities. Information in Chapter 6 of this document can be adapted and supplemented with specific information for a chapter covering statutory and regulatory requirements in an environmental assessment or environmental impact statement. People preparing environmental assessments and EISs should also be cognizant of the document titled Recommendations for the Preparation of Environmental Assessments and Environmental Impact Statements published by the DOE Office of NEPA Oversight. (a) PNNL staff prepared individual sections of this document, with input from other Site contractors. More detailed data are available from reference sources cited or from the authors. Sections were updated with the best available information through June 2001. Any interested individual seeking baseline data on the Hanford Site and its past activities may also use this information by which to evaluate projected activities and their impacts. The following personnel are responsible for the various sections of this document and can be contacted with questions: