Stormwater Management Measures

The City of San José is responsible for ensuring compliance with federal and state laws that regulate stormwater runoff into the storm drain system, streams, rivers and the San Francisco Bay.

The Planning Division requires applicants for new development sites or redeveloped sites to submit the appropriate forms, plans, and measures pertaining to stormwater regulations -- specifically the NPDES Provision C.3 regulation -- as part of their planning permit. Learn more by continuing to read this webpage.

The Environmental Services Department (ESD) inspects onsite stormwater treatment features to ensure they are maintained and functioning. Learn more at the ESD Stormwater Treatment Features webpage.

Helping Development Projects Comply with NPDES Provision C.3

The City operates under the Municipal Regional Stormwater NPDES Permit (MRP), issued by the Regional Water Quality Control Board. Provision C.3 of the MRP requires new and redeveloped projects to include measures to both treat and prevent increases in runoff. Provision C.3 is implemented through:

City Council Policy 6-29: Post-Construction Urban Runoff Management; and
City Council Policy 8-14: Post Construction Hydromodification Management.

These policies apply to Regulated Projects and emphasize the use of Low Impact Development measures.

C.3 Stormwater Handbook

The C.3 Stormwater Handbook for Santa Clara County contains guidance to assist project applicants, developers, and builders to create projects with stormwater control plans that include appropriate post-construction site design, source control, and treatment control measures. Please keep in mind that requirements may vary from one local jurisdiction to the next. Contact your Planning project manager if you have questions about how these requirements will apply to your specific project. In the case of conflicting information between this handbook and the MRP, the MRP requirements prevail.

Application Requirements

All Regulated Projects must complete the following forms and worksheets. These forms must be submitted with the Permit Application and copied onto the Stormwater Control Plan. Refer to the application instructions for all remaining information that must be included throughout the plan set.

Required Forms

Land Uses of Concern

Certain land uses have the potential to create contaminated stormwater runoff. Stormwater runoff from these uses requires special consideration and treatment measures. This includes a Stormwater Control Plan with specific Source Control Measures (not numerically sized) and an Installation, Operation & Maintenance plan regardless of project size or amount of new impervious area proposed for the development.

Land Uses of Concern include, but are not limited to:

Any industrial use
Car washing and detailing facilities
Construction/corporation yards
Automotive uses including but not limited to dismantling, parts recovery, and vehicle repair
Material recycling facilities (processing, transfer and large collection facilities)
Outdoor Storage
Gas stations or equipment fueling
Uncovered parking lots
Loading docks
Restaurant activities
Trash and recycling areas

For more information about these uses and measures for treatment, refer to the City Council Policy 6-29: Post-Construction Urban Runoff Management and C.3 Stormwater Handbook.

Low Impact Development

Regulated Projects must provide a Stormwater Control Plan that describes and illustrates the exclusive use of Low Impact Development (LID) measures. Provision C.3.c of the Municipal Regional Stormwater NPDES Permit requires each Regulated Project to treat 100% of a project’s stormwater runoff with LID treatment measures as of December 1, 2011.

LID measures include:

preserving existing open space areas and reducing the amount of impervious surfaces (Site Design);
preventing stormwater runoff from coming into contact with pollutants (Source Control);
removing pollutants from stormwater runoff (Treatment); and
retaining or detaining runoff (Hydromodification).

LID Treatment Measures include:

Infiltration;
Evapotranspiration; and
Biotreatment.

Infiltration is the preferred method. Biotreatment is only permitted if Infiltration and/or Harvest and Use are infeasible. There is no separate evapotranspiration treatment measure because this process occurs naturally in infiltration, harvest and use, and biotreatment.

The standards for determining if infiltration is feasible or infeasible are based on a report by Geosyntec Consultants: BASMAA Harvest and Use, Infiltration and Evapotranspiration Feasibility/Infeasibility Criteria Report. The process to determine which Treatment Measure is appropriate to use is described under Application Requirements.

For more information about these using these techniques, refer to the C.3 Stormwater Handbook. (updated C.3 Handbook website)

Regulated and Special Projects

For purposes of assigning appropriate stormwater treatment measures, the Municipal Regional Stormwater Permit (MRP) categorizes development projects as follows:

Regulated Projects - Must submit a Stormwater Control Plan (see below for details); or
Special Projects - A type of Regulated Project that must also submit a Stormwater Control Plan. May use alternative means of treatment depending on specific criteria (see below for details).

Regulated Projects

Regulated Projects must submit a Stormwater Control Plan that includes Site Design Measures, Source Control Measures, and hydraulically sized Low Impact Development (LID) Treatment Measures. See these documents for details on the measures to include:

In addition, temporary emergency housing projects are not subject to Treatment System requirements and instead must implement Site Design Measures and relevant Best Management Practices see Stormwater Evaluation Form

There are several categories of Regulated Projects:

Special Land Use Categories - These are any auto service facilities, retail gasoline stations, restaurants, and/or uncovered or standalone (or part of a larger project) parking areas that create, replace, or expand the amount of impervious areas by 5,000 square feet or more.
Other Development & Redevelopment Projects - Qualifying new development or redevelopment projects are projects that create, replace, or expand the amount of impervious surface by 5,000 square feet or more. Redevelopment is any land-disturbing activity that results in the creation, addition, or replacement of exterior impervious surface area on a site where past development has occurred. New development and redevelopment projects may qualify for alternative means of compliance with Provision C3 through the use of smart growth, high density, and/or affordable housing; see the Special Projects section below.
New or Widening Road Projects - These are road projects that create 5,000 square feet or more of newly constructed contiguous impervious surface. These include construction of new streets or roads (including sidewalks and bicycle lanes), widening of existing streets or roads with additional traffic lanes, and construction of impervious trails greater than or equal to 10 feet wide or are creek side.
Road Reconstruction Projects - Road projects that involve the reconstruction of existing streets or roads, which create or replace one contiguous acre or more of impervious surface, including utility trenching projects that are on average eight feet wide or more over the entire length of the project.
Detached Single-Family Home Projects - These are detached single-family home projects that create or replace 10,000 square feet or more of impervious surface, including accessory dwelling units.
Hydromodification Management Projects (HMP) - HMP projects are located in a green area of the Hydromodification Applicability Map that create and/or replace one acre or more of impervious surface and increases the amount of impervious areas above the pre-project conditions. Projects that meet this criteria must submit a Hydromodification Plan that meets the requirements of the Municipal Regional Stormwater NPDES Permit as detailed in the Post Construction Hydromodification Management policy.

50% Rule – This rule applies to all Regulated Project categories:

If a project results in an alteration of 50% or more of the total amount of impervious area from a previously approved project/existing area, then runoff from the entire project must be included in the treatment system design.
If a project results in an alteration of less than 50% of the total amount of impervious area from a previously approved project/existing area, then only the new and/or replaced impervious surface of the project must be included in the treatment system design.

Special Projects

The Municipal Regional Stormwater Permit (MRP) allows certain types of smart growth, high density, and affordable housing development to use alternative means of treatment depending on specific criteria. These types of qualifying projects, known as Special Projects, can apply for alternative means of Low Impact Development (LID) stormwater treatment which may include non-LID methods in addition to LID practices of infiltration, harvest and use and biotreatment to manage stormwater runoff.

Refer to the Special Projects Category A and B Map and Special Projects Category C Map to determine if you meet one of the three following categories to qualify for a reduction of the LID requirements:

Category A (Small Infill) - Located in a San José designated Downtown core area or Downtown core zoning district, neighborhood business district, or historic preservation district; 0.5 acres or less; no surface parking (except incidental, see MRP); maximum 85% coverage.
Category B (High Density) - Located in a San José designated Downtown core area or Downtown core zoning district, neighborhood business district, or historic preservation district; 0.5 acres up to 2.0 acres; no surface parking (except incidental, see MRP); maximum 85% coverage; minimum density of 50 dwelling units per acre (for residential projects) or a Floor Area Ratio (FAR) of 2:1 (for commercial or mixed use projects).
Category C (Affordable Housing) - Project must be primarily a residential development project and achieve at minimum a gross density of 40 dwelling units per acre.

Qualifying projects may apply for reduction credits based on location and density criteria that allow non-LID treatment for a portion of the project’s runoff, but only after the applicant demonstrates why LID is infeasible for the proposed project. The LID reduction credits are intended to allow Smart Growth and affordable housing projects greater flexibility in meeting stormwater treatment requirements, based on the inherent environmental benefits of Smart Growth, affordable housing, and potential technical challenges of implementing LID treatment exclusively on high-density sites in urban areas.

Project applicants may use the Special Projects Worksheet and Appendix J (Section J.7) of the C.3 Stormwater Handbook to determine if a project meets the specific criteria that allows treatment reduction credits.

The final determination to allow non-LID treatment measures is based on whether or not onsite and/or offsite LID treatment is feasible or infeasible, subject to the City’s review and approval. Site design and source control measures are still required for all Regulated Projects.

Application Requirements

REQUIRED FORMS