Stormwater C.3 Guidebook

Stormwater C.3 Guidebook 6th Edition and Addenda

Click on this link to download the Stormwater C.3 Guidebook 6th Edition (February 15, 2012, 2.0 MB .pdf formatted for 2-sided printing).

Here is a memorandum describing changes from the Guidebook 5th Edition.

Addenda and updates to the 6th Edition

  • Click here to download the updated bioretention soil media specification approved April 18, 2016. (See BASMAA and Executive Officer letters for an explanation of the changes.)
  • Click here to download the March 2016 “Stormwater C.3 Update.” The update is an addendum to the C.3 Guidebook, 6th Edition, and incorporates key changes to Provision C.3 in the Municipal Regional Stormwater Permit (MRP 2.0).
  • Click here to download the March 20, 2013 Guidebook Addendum, “Contra Costa Clean Water Program Technical Criteria for Non-LID Facilities.” These criteria apply to tree-box-type high-flowrate biofilters and vault-based high-flowrate media filters when proposed for use on Special Projects (see the Guidebook 6th Edition, page 58).
  • Click here to download the December 1, 2012 Guidebook Addendum, “Preparing a Stormwater Control Plan for a Small Land Development Project,” in compliance with Municipal Regional Permit Provision C.3.i. The guidance applies to projects that create or replace 2,500 square feet or more, but less than 10,000 square feet, of impervious surface.

Additional Guidebook Resources

Stormwater Control Plan Template

The template is updated and consistent with the Stormwater C.3 Guidebook 6th Edition (138KB .doc).

IMP Sizing Calculator

Released October 2009. Consistent with the 6th Edition. Be sure to review and follow Guidebook instructions for preparing a complete Stormwater Control Plan. Calculator and setup file (3MB .zip). After installing the calculator, read the help file. If attempting to run the calculator results in an error message, try right-clicking the icon and selecting “Run as Administrator.”

Appendix A: Local Exceptions and Requirements

Municipality-specific procedures, policies and submittal requirements should be obtained from the municipality’s planning and community development department.

Follow the link to the local municipality website:

Appendix B: Soils, Plantings, and Irrigation for Bioretention Facilities

The soil specification approved April 18, 2016 includes the following statement: “Local soil products suppliers have expressed interest in developing ‘brand-name’ mixes that meet these specifications. At their sole discretion, municipal construction inspectors may choose to accept test results and certification for a ‘brand-name’ mix from a soil supplier.”

For the convenience of the land development community, the Contra Costa Clean Water Program invited local soil suppliers to request listing here. The following suppliers submitted test results and certifications. Listing does not imply or guarantee that the mix as designed or delivered meets all requirements of the soil specification. Contractors and construction inspectors should independently obtain and review the required information before approving installation of a ‘brand-name’ soil mix.


Policies and content of the following memoranda have been incorporated into the 6th Edition. The memoranda include some additional background and explanatory material.

Guidance for HSPF Modeling (for Hydromodification Management)

For compliance with flow-control requirements using Option 3 in Appendix C of the 6th Edition (memo 763 KB .pdf)

Basic Geomorphic Assessment Methods and Criteria

For compliance with flow-control requirements using Option 4b in Appendix C of the 6th Edition. Contact the Program to obtain a copy.

Contra Costa Hydrology Data

Example Stormwater Control Plans

Please note these example plans were prepared in compliance with previous editions of the Stormwater C.3 Guidebook. They are made available as examples for format and presentation.

Operation and Maintenance of Stormwater Facilities


The following documents are in MS Word and may be incorporated into Stormwater Facilities Operation and Maintenance Plans. See Chapter 6 of the Stormwater C.3 Guidebook, 6th Edition

Operation and Maintenance Fact Sheets

The following fact sheets provide general information on maintenance of stormwater facilities. In the Stormwater Facilities Operation and Maintenance Plan, this information should be augmented with information specific to the facility and the site.


Example Operation and Maintenance Plans

The following plan is provided as an example. Requirements tend to be project-specific and should be discussed with staff of the municipality having jurisdiction.

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