Hydromodification Management (HM) Applicability Map

(New!) View the CCCWP 2023 HM Applicability Map, Web Application Format ( (approved February 1, 2024).  The CCCWP 2023 HM Applicability Map should be used for rapid initial determination of whether location-based HM requirements apply to proposed land development projects in jurisdictions across Contra Costa County. This web mapping application can be used by municipal staff, applicants for development project approvals, and the public.  Further information and the final resources are provided on Stormwater C.3 Guidebook webpage.

Important Note: These documents have been formally approved by the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) Executive Officer (EO) after having been submitted to SFBRWQCB as part of 2022-2023 Annual Reporting requirements.  

(Archived) Hydrograph Modification Management Plan

Note: As of December 2022, CCCWP decided to adopt the Bay Area Hydrology Model (BAHM), and has worked with Clear Creek Solutions to incorporate Contra Costa rainfall data into the model.  Further information and resources are provided on Stormwater C.3 Guidebook webpage.

(Archived) Hydromodification Management Submittals (2007-2017)

(Archived) Hydrograph Modification Management Plan Submittals (2004-2005)

(Archived) Appendix B to Attachment 4: Sample Stream Stability Handbook Sheets

Other Submittals to the Regional Water Quality Control Boards