Water resources policies & procedures

Follow the policies and procedures on this page to help protect and improve natural habitat and water quality, manage and minimize affects from our daily activities and construction projects, comply with regulations, and achieve the Washington State Department of Transportation’s (WSDOT) strategic plan goal for environmental stewardship.

See our Wetlands pages for more information on addressing requirements directly related to assessing and mitigating wetland impacts.

See our Erosion control policies & procedures page for more information on temporary erosion and sediment control and applying for and complying with the Construction Stormwater General Permit (CSWGP).

Find additional policies and procedures by topic below:


Consider impacts to groundwater in the context of overall water quality as well as a source of drinking water.

Register new Underground Injection Control (UIC) wells

UIC wells include drywells and infiltration trenches with perforated pipe. To register a new UIC, fill out Ecology’s UIC Registration Form and submit it to Cory Simon, Cory.Simon@wsdot.wa.gov.

Read Chapter 433: Groundwater of the Environmental Manual for legal requirements and policy context for groundwater impact analyses. Use the guidance and checklist below to analyze groundwater impacts and develop a discipline report to support NEPA/SEPA documentation.

Surface water

Impacts to surface water can be from work in, over, or near water bodies. Impacts could also come from erosion, spills, and increasing pollutants or flow volumes to water bodies from stormwater runoff.

Read Chapter 430: Surface Water of the Environmental Manual for legal requirements and policy context for surface water impact analyses. Use the guidance, checklists, and links below to analyze surface water impacts and create NEPA/SEPA documentation.


Untreated and uncontrolled flows of stormwater runoff from highways and construction sites can adversely impact water quality and habitat in receiving surface water bodies and groundwater. Use the information below to help minimize these impacts from stormwater as well as stay in compliance with our stormwater permits.

Stormwater permits

Find more information about stormwater permits on the Clean Water Act, Section 402 – National Pollutant Discharge Elimination System (NPDES) permits webpage.

Stormwater Management Program Plan

Find information about implementing stormwater permit requirements on the Managing stormwater from state highways webpage.

Report spills and eliminate illicit discharges

Find procedures for identifying and reporting spills, illicit discharges, and unauthorized connections that might affect WSDOT’s stormwater drainage system and receiving water bodies on the Reporting spills & eliminating illicit discharges webpage.

Identify Total Maximum Daily Load (TMDL) and impaired water bodies

During project scoping, find out if your project will discharge stormwater to an impaired water body. Impaired water bodies include those on the 303(d) list or covered by a Total Maximum Daily Load (TMDL). Follow the instructions for identifying impaired water bodies for the Environmental Review Summary (ERS) (pdf 284 kb), and plan ahead to avoid impacts to the impaired water bodies.

Inventory stormwater discharge points

When preparing the hydraulics report for your project, use the instructions, definitions, and form below to document stormwater discharges.

Stormwater impact assessment

Find information about assessing the environmental effects of stormwater and the construction of stormwater best management practices (BMPS) on a project site on the Stormwater guidance for Biological Assessments webpage and in Chapter 17 of the Biological Assessment Manual (pdf 906 kb)

Implement stormwater retrofit solutions

Many existing highways either do not have any stormwater flow control or treatment facilities, or do not have enough to manage the runoff from all impervious surfaces. To help improve stormwater management in these areas and comply with permits, use the information below when planning and scoping projects:

  • To determine the retrofit obligations and identify stormwater retrofit opportunities for your project, follow the guidelines in Section 3-4 Stormwater Retrofit Guidelines of the Highway Runoff Manual.
  • Before scoping, read the Stormwater Retrofit Guidance section on the Highway Runoff Manual webpage which includes considerations for scoping stand-alone stormwater retrofits, a site visit checklist, and instructions for determining cost-effectiveness and feasibility of stormwater retrofits.
  • To find out if an area is in a high, medium, or low priority area for stormwater retrofit, contact Sheena Pietzold, Sheena.Pietzold@wsdot.wa.gov.
  • Find more information about WSDOT's Stormwater Retrofit Program and our approach to prioritizing retrofits in the Stormwater Retrofit Management Plan (pdf 1.58 mb).

Quality Assurance Project Plans (QAPPs)

A QAPP describes the objectives of a monitoring study and the procedures to follow to ensure the quality and integrity of collected data and ensure the results are representative, accurate, and complete. To request copies of our stormwater monitoring QAPPs, contact Brad Archbold, Brad.Archbold@wsdot.wa.gov.

Standard Operating Procedures (SOPs)

SOPs describe procedures to follow for completing specific tasks. To request copies of our SOPs, email the contact related to the tasks below.


Local agencies often manage floodplain development. Find information about floodplain development permits on the Local permits and approvals webpage.

Read Chapter 432: Floodplains of the Environmental Manual for the legal requirements and policy context for floodplains impact analyses. Use the guidance and checklist below to analyze floodplain impacts and develop a discipline report to support NEPA/SEPA documentation.

Geology & soils

Consider topographic and geologic conditions as well as significant landforms, soil types, and geologic hazards when planning work and assessing project alternatives.

Read Chapter 420: Earth (Geology and Soils) of the Environmental Manual for the legal requirements and policy context for geology and soils impact analyses. Use the guidance and checklist below to analyze geology and soils impacts and develop a discipline report to support NEPA/SEPA documentation.