Frequently Asked Questions

The Standard Urban Stormwater Mitigation Plan (SUSMP) was adopted by the City of Poway to meet a requirement of the Municipal Storm Water Permit from the California Regional Water Quality Control Board. Because anything that enters the storm drain system flows directly to creeks, lakes and the ocean, SUSMP is intended to reduce post-construction urban runoff and water pollution from types of projects considered most likely to cause runoff or pollution.

Any type of development can generate pollutants such as trash, oil leaking from cars, fertilizers, pesticides, and more. In addition, replacing areas where plants normally grow with impervious surfaces, such as pavement or buildings, reduces the amount of storm water that can soak into the ground and increases runoff. Increased runoff can cause erosion problems and also carries pollutants into the storm drain system, where they flow untreated into creeks, lakes and the ocean.

A project is subject to SUSMP requirements if it falls in any of the following categories:

• Pollutant-generating development project - 1 acre or more
• Residential development of 10 or more units
• Commercial development greater than 100,000 square feet
• Automotive repair shop
• Restaurant
• Steep hillside development greater than 5,000 square feet
• Creation of 2,500 square feet or more of impervious surface with discharge of runoff to an Environmentally Sensitive Area
• Parking lot larger than 5,000 square feet or with more than 15 parking spaces
• Street, road, highway, or freeway that adds more than 5,000 square feet of new paved surface
• Significant redevelopment that adds 5,000 square feet or more of new impervious surface

The city will check to see that the applicant has identified all of the pollutants that could be generated by the proposed development, as well as any pollutants that already impair the quality of the water body to which the project drains. The drainage study report will be reviewed to ensure that the effects of the project on the rate and volume of runoff are identified.

The city will then check to ensure that each potential pollutant and all flow issues are addressed through the use of 3 types of Best Management Practices (BMPs):

• Site Design (minimizing increases in runoff)
• Source Control (reducing the amount of pollution generated)
• Treatment Control (removing pollutants from runoff)

Streets, sidewalks and parking lot aisles should be kept as narrow as standards allow. Minimizing impervious surfaces and conserving natural areas and natural drainage systems reduces runoff and helps filter some types of pollutants. Making sure that all impervious surfaces drain to landscaped areas also helps storm water to soak into the ground rather than running off into the drainage system.

Cover all outside storage containers, trash bin structures, fueling and maintenance areas and similar areas, and design them to ensure they prevent contact between potential pollutants and storm water. Hillsides should be landscaped to prevent erosion. Stenciling storm drains reduces illegal dumping and reminds everyone that whatever goes into the storm drain will flow untreated into waterways.

Grassy swales, constructed wetlands, and infiltration structures can act as biofilters to remove pollutants from runoff. Detention basins allow suspended pollutants to settle out, where they can be properly disposed of later. In some cases, filtration systems or drainage inserts can be used to filter pollutants from flowing into storm drains or other bodies of water.

To be effective at reducing pollution, the Best Management Practices (BMPs) must be maintained regularly. For all private projects, it is the owner’s responsibility to maintain the BMPs in perpetuity. The city periodically inspects BMPs to ensure they continue to function as designed.

The full text of the SUSMP requirements can be found in the Poway Local SUSMP, which is available in the Development Services Department, Land Development Engineering Division. These requirements have been incorporated in Chapters 16.100 through 16.105 of the Poway Municipal Code (PMC). Handbooks that give additional information on the design and implementation of BMPs can be found online.

For more information, please contact Development Services at 858-668-4600, or visit the Development Services counter on the 1st floor of Poway City Hall at 13325 Civic Center Drive.