The Environmental Manual M 31‑11 is a compilation of environmental policies and processes that is to be used as a guidance resource for the Washington State Department of Transportation (WSDOT) and its environmental consultants. The Environmental Manual outlines WSDOT’s legal requirements related to environmental, cultural, historic, and social resources and is a keystone of WSDOT’s environmental compliance strategy.
The information contained in the Environmental Manual supplements the wide range of technical expertise among WSDOT Engineering, Environmental, Highway and Local Programs, and Planning staff, as well as local agencies and consultants. It provides consistent, current, and accurate guidelines for complying with federal and state environmental laws and regulations for all phases of project delivery. The guidance provided by the Environmental Manual assists WSDOT project proposals by encouraging early consideration and documentation of environmental issues during project scoping, alternative development, and preliminary design. It also provides guidance on complying with environmental requirements during the construction and maintenance phases of a project as well as addressing utilities and surplus property sales.
This manual includes information from many sources other than WSDOT, including a variety of state and federal agencies. Every effort has been made to make this information as current as possible. However, it is the user’s responsibility to ensure that any action taken to comply with the excerpted or referenced material is based on the most current information available from these outside sources.
Updating this manual is a continuing process, due to the ever‑changing status of environmental policies. Users are encouraged to submit the Feedback Form on page v to help guide future updates.
Contents (PDF 174KB)
Exhibits (PDF 174KB)
Chapter 100 Purpose and Overview (PDF184KB)
Chapter 200 Environmental considerations in transportation planning (PDF 274KB)
Chapter 300 Project scoping and programming (PDF 329KB)
Chapter 400 Environmental review (NEPA/SEPA) and transportation decision making (PDF 592KB)
Chapter 412 Indirect and cumulative impacts (PDF 524KB)
Chapter 420 Earth (Geology and Soils) (PDF 154KB)
Chapter 425 Air Quality, Greenhouse Gases, Energy (PDF 312KB)
Chapter 430 Stormwater and Water quality (PDF 341KB)
Chapter 431 Wetlands (PDF 223KB)
Chapter 432 Special Flood Hazard Area (PDF 803KB)
Chapter 436 Fish, wildlife and vegetation (PDF 453KB)
Chapter 447 Hazardous Materials and Solid Waste (PDF 275KB)
Chapter 455 Land Use and Transportation (PDF 385KB)
Chapter 456 Cultural resources (PDF 527KB)
Chapter 457 Section 4(f) evaluation (PDF 399KB)
Chapter 458 Social and community effects (PDF 313KB)
Chapter 459 Visual impacts (PDF 313KB)
Chapter 460 Environmental justice (PDF 330KB)
Chapter 490 Tracking environmental commitments during design (PDF 208KB)
Chapter 500 Environmental permitting (PDF 279KB)
Chapter 530 Tribal Approvals (PDF 207KB)
Chapter 590 Incorporating environmental commitments into contracts during PS&E (PDF 343KB)
Chapter 600 Construction (PDF 335KB)
Chapter 700 Maintenance and Operations (PDF 325KB)
Chapter 800 Property Management and Disposal (PDF 225KB)
Appendix A Executive Orders (PDF 120KB)
Appendix B Interagency Agreements (PDF 145KB)
Appendix C Letters, Memos and Directives (PDF 1.2MB)
Slow down – lives are on the line.
In 2022, speeding continued to be a top reason for work zone crashes.
Even one life lost is too many.
Each year about 670 people are killed nationally in highway work zones. In 2022, Washington had six fatal work zone crashes on state roads.
It's in EVERYONE’S best interest.
95% of people hurt in work zones are drivers, their passengers or passing pedestrians, not just our road crews.