Stormwater Design Manual

The Stormwater Design Manual is compatible with the Minimum Design Criteria (MDC) that are codified in the stormwater rules, which went into effect on Jan. 1, 2017.  The Stormwater Program will periodically update the Manual to provide better guidance on meeting the stormwater rules.  Chapters C-1 through C-12 were updated on November 20, 2020.

Sign up for the Stormwater Design Manual Email List


Supplement EZ form (12/3/2020)

O&M EZ form (12/15/2020)

SCM Crediting

Stormwater Control Measure Credit Document (2/27/2023):  This document lists all SCM credits together to facilitate comparisons between different SCMs for the regulated community and includes information on the New Stormwater Technology (NEST) Program. It is a joint effort between DEQ’s Stormwater and Nonpoint Source Planning programs.

Stormwater Design Manual Table of Contents

Part A: Common Site and SCM Elements

A-0.     Areas of Research Needed (8/15/2019)

A-1.     Runoff Treatment & Volume Match  (4/3/2017)

The Department is working on replacement for the defunct “Storm-EZ” spreadsheet and improving the guidance in Part A-1 of the Manual for demonstrating that a project has met runoff volume match.

A-2.     Soils (4/3/2017)

A-3.     Vegetation (4/3/2017)

A-4.     Built-Upon Area (2/11/2018)

A-5.     Common Structures and Materials (2/11/2018)

A-6.     Construction  (2/11/2018)

A-7.    Operation and Maintenance  (2/11/2018)

A-8.    Guidance on SCM Selection  (7/24/2018)

A-9.    Vegetated Setbacks  (7/30/2019)

Part B: Calculations Guidance (3/15/2017)

Part C: Minimum Design Criteria and Recommendations for Stormwater Control Measures

C-0.     MDC for all SCMs (1/3/2017)

C-1.     Infiltration System (11/20/2020)

C-2.     Bioretention Cell (11/20/2020)

C-3.     Wet Pond (11/20/2020)

C-4.     Stormwater Wetland (11/20/2020)

C-5.     Permeable Pavement  (11/20/2020)

C-6.     Sand Filter  (11/20/2020)

C-7.     Rainwater Harvesting  (11/20/2020)

C-8.     Green Roof (11/20/2020)

C-9.     Level Spreader-Filter Strip (11/20/2020)

C-10.   Disconnected Impervious Surface (11/20/2020)

C-11.   Treatment Swale (11/20/2020)

C-12.   Dry Pond (11/20/2020)

Part D: Minimum Design Criteria and Recommendations for New Stormwater Technologies

D-1.     StormFilter  (1/3/2017)

D-2.     Silva Cell Suspended Pavement with Bioretention (8/7/2017)

D-3.     Filterra (2/11/2018)

D-4.     BayFilter (2/9/2018)

Part E: Guidance for Specific Types of Sites

E-1.     Low Density  (2/11/2018)

E-2.     Single Family Homes with BUA Limits (4/6/2017)

E-3.     Retrofits (1/3/2017)

E-4.     Airports (1/29/2018)

E-5.     Linear Transportation and Greenways (1/3/2017)

E-6.     Solar Farms (12/13/18)

Part F: Guidance for New Stormwater Technologies: Information on the New Stormwater Technology (NEST) Program has been moved to the Stormwater Control Measure Credit Document (2/27/2023).



MDC Team: Documents all of the discussions from the stakeholders group that developed the new Minimum Design Criteria