2007 MS4 Permit Publications
Countywide Model SUSMP
The Stormwater Copermittee Land Development Workgroup is responsible for the development and update of the Countywide Model Standard Urban Stormwater Management Plan (SUSMP) and Hydromodification Management Plan (HMP), as well as related tools and resources. Workgroup information can be found here.
Final Countywide Model SUSMP (March 2011)
Appendix A- Stormwater Pollutant Sources/Source Control Checklist
Appendix B – Final Hydromodification Management Plan
Countywide Hydromodification Plan
Regional Water Quality Control Board Order R9-2007-0001 Provision D.1.g (6) (Board Order) requires the County of San Diego and its NPDES Co-permittees to develop a Hydromodification Plan to manage the increases in runoff discharge rates and durations from all Priority Development Projects, where such increased rates and durations are likely to cause erosion of channel beds and banks, sediment pollutant generation, or other impacts to beneficial uses and stream habitat due to increased erosive force.
A key element of the creation of the San Diego HMP is the involvement of a Technical Advisory Committee (TAC). The TAC members consist of respected individuals from academia, technical resource agencies, the development community, consulting engineers, and environmental organizations. The TAC was tasked with providing technical input to the scientific approach and interpretation of results integral to the establishment of numerical flow control standards for the HMP.
The HMP can be found as an appendix to the Model SUSMP and below. Any priority development project subject to SUSMP requirements is also subject to HMP requirements.
Final Hydromodification Management Plan
The following report provides an evaluation of the two alternative methods, HSPF watershed model and San Diego Hydrology Model, for satisfying the HMP, and is intended to provide the San Diego Copermittees with a clear understanding of the applicability, functions, and results of these tools. Both software tools, are reviewed for compliance with the HMP and standard stormwater management methodology.
Hydromodification Software, Third Party Review
The San Diego BMP Sizing calculator provides a simplified method for sizing BMPs to comply with treatment control and hydromodification management requirements without project specific continuous simulation. The following links provide the background for the methodology, the spreadsheet calculator, and the user guide.
San Diego BMP Sizing Calculator Methodology
BMP Sizing Spreadsheet V1.04
BMP Sizing Spreadsheet User Guide V1.04
The San Diego Hydromodification Management Plan (HMP) has been implemented over the past 5 years. Detailed results of the monitoring program have been presented in a series of annual monitoring reports between 2011 and 2016. This Final HMP Report compiles and summarizes the results and findings of the five year field monitoring and desk-top analyses. This Final HMP Report includes the following monitoring and technical reports as exhibits that provide discussions that are more detailed and data from which the conclusions in this report are based.
HMP Monitoring Report
HMP Monitoring Report Exhibit A
HMP Monitoring Report Exhibit B
HMP Monitoring Report Exhibit B Appendix D
HMP Monitoring Report Exhibit C
HMP Monitoring Report Exhibit D
HMP Monitoring Report Exhibit E
HMP Monitoring Report Exhibit F
Low impact development (LID) is a term used to describe a land planning and engineering design approach to managing stormwater runoff. LID emphasizes conservation and use of on-site natural features to protect water quality. This approach implements engineered small-scale hydrologic controls to replicate the pre-development hydrologic regime of watersheds through infiltrating, filtering, storing, evaporating, and detaining runoff close to its source.
Excellant information is available at the following resources:
California Low Impact Development Web Portal
Low Impact Development Center
Low Impact Development Urban Design Tools
USEPA Low Imapct Development Resources
NRDC Low Impact Deveopment – Stormwater Strategies
County of San Diego Low Impact Development Handbook with Appendices (July, 2014)