Frequently Asked Questions

Structural BMPs are devices or landscape features that help to prevent pollutants in storm water runoff from leaving a developed property, entering our storm drains, and impacting our local waterways. All types of structural BMPs require regular inspection and maintenance to ensure that they are operating effectively.

Examples of device-type Structural BMPs include drain insert filters, hydrodynamic separator structures, manufactured filtration systems, and underground storage vaults. Landscape feature-type Structural BMPs are vegetated and go by various names, including vegetated swales, bio-swales, bioretention basins, and biofiltration basins. Some proprietary biofiltration systems combine manufactured structures and vegetation into one Structural BMP.

Because it's the law. San Diego Regional Water Board MS4 Permit has required structural BMPs (formerly treatment control BMPs) for certain new and redevelopment projects since 2002. The City's Storm Water Design Manual (PDF) for priority development projects includes an overview about inspection and maintenance for specific types of BMPs. Structural BMP information is also available through CASQA.

Land development projects generally alter the natural conditions of the land by removing vegetative cover, compacting soil, and constructing impervious surfaces like streets, sidewalks, parking lots, and buildings. Unlike natural landscapes, impervious surfaces associated with development do not allow natural processes of infiltration, retention, and evapotranspiration of storm water to take place. Impervious surfaces also generate increased amounts of storm water runoff that can carry pollutants such as trash, fertilizers, pesticides, oils, metals, and sediment into our watersheds. Increased runoff volumes, discharge rates, and velocities also adversely impact stream habitat by causing unnatural erosion of creek beds and banks. To reduce the negative impact storm water runoff can have on our local waterways, certain developed properties are required to install and maintain structural BMPs.

If your property was developed or re-developed since 2002, you may have been subject to BMP requirements depending on the applicable criteria in force at the time. Property owners and property managers should be able to locate and identify the required structural BMPs on your property. Structural BMP requirements "run with the land," so if you have recently purchased a property with structural BMPs, you are responsible for performing the required maintenance. Structural BMPs should not be removed or altered without prior approval from the City.

BMP information should be documented on each development's grading plans in addition to an approved Water Quality Technical Report (prior to 2013) or Storm Water Quality Management Plan (2013 to present). These documents would have been prepared by a licensed engineer as part of a property's development approvals.

If you need assistance with identifying and locating your BMPs, please email Environmental Programs or call 760-839-4074. Please provide your property address or the Project ID that appears on your maintenance certification form.