Green Stormwater Infrastructure (GSI)

GSI cross section illustration annotated

Green stormwater Infrastructure (GSI) helps improve water quality, prevent flooding and replenish ground water. GSI uses specially engineered planted areas, filtration systems, and water permeable hardscapes to collect and clean water from roofs, streets, sidewalks, and other impervious surfaces.  California law requires GSI or other stormwater treatment for new and/or redevelopment projects over specified sizes, depending on the project type. 

Summary slides explaining GSI (Coming soon)

California State Water Resource Control Board GSI requirements

See section C.3 of the Municipal Regional Stormwater Permit (MRP)

Is GSI required for my project?

  • Table of project type, size, and requirements by past and current MRP

For City of Oakland staff only:

Where’s GSI in Oakland?

Technical documents - Design specifications, CAD files, delineation and sizing instructions, etc.

  1. City of Oakland GSI guide (2025) – introduces green stormwater infrastructure and describes why and when it is needed, how it works, and provides details on siting, selecting, sizing, and tracking facilities.(PDF, 2MB)
  2. Brief guide of GSI types(PDF, 1MB)
  3. GSI siting constraints annotated list – (utilities, building setbacks, bike lanes, etc.)(PDF, 142KB)
  4. GSI Drainage area delineation guide – why and how to map areas treated by GSI, and how to report into regional databases(PDF, 3MB)
  5. GSI instructions for City-hired consultants – guide to developing plan sets and completing plan checks from conceptual designs through 100% plans, and construction.(PDF, 22MB)
  6. City of Oakland GSI technical design details and specifications(PDF, 4MB)
  7. C.3 Technical Guidance Manual (updated 2024) – Alameda Countywide guidance for GSI design requirements
  8. CAD files for GSI technical design details(ZIP, 11MB)
  9. Guidance for Sizing (NON-REGULATED ONLY) Green Infrastructure Facilities in Street Projects (BASMAA)  

 

Plant species lists for GSI

GSI plant guide and list – species selection and procurement, propagation, irrigation, monitoring and maintenance(PDF, 590KB)

 

GSI Maintenance resources

City of San Jose GSI Maintenance Field Guide: Instruction, standards, and guidelines on inspection and maintenance of GSI projects. This is a good overview, though a simpler grading scale (good, moderate, poor) is recommended and a corresponding maintenance sheet has been developed.

 

Asbuilts for City GSI

Asbuilts of completed City owned GSI (accessible by City of Oakland staff only)

 

Operations and Maintenance agreements for Privately Owned GSI

Coming soon - Accessible by City of Oakland staff only

 

Stormwater Management Resources Around Homes

 

Additional Resources

Alameda Countywide Clean Water Program Green Infrastructure website

 

Questions/comments

Contact Watersheds@oaklandca.gov

 

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