According to the 1996 National Water Quality Inventory, stormwater runoff is a leading source of water pollution and can harm surface waters such as lakes, rivers, streams and wetlands. Common pollutants in stormwater runoff include pesticides, fertilizers, oils, metals, pathogens, salt, sediment, litter and other debris. These pollutants are transported via stormwater from a variety of sources including construction projects, industries and urbanized areas.
Management of stormwater runoff from urbanized areas is very important for restoring or protecting surface waters. Urbanized areas are associated with activities that contribute pollutants to stormwater runoff, such as application of anti/deicing compounds, vehicle fueling, spills, landscaping and lawn maintenance, and application of pesticides and fertilizers. Additionally, urbanized areas are characterized by large amounts of impervious surfaces, such as streets, driveways, roof tops, parking lots and sidewalks. Stormwater runoff from impervious surfaces travels faster and in larger quantities, which results in damage to rivers, streams and wetlands; destruction of aquatic habitats; and elevated pollutant levels reaching surface waters. Impervious surfaces also inhibit infiltration and subsequent groundwater recharge. Local public entities that own or operate a municipal separate storm sewer system (MS4) in urbanized areas play a key role in preventing or reducing the negative impacts stormwater runoff may have on Minnesota’s valuable water resources.
Maintenance is necessary for a stormwater best management practice (BMP) to operate as designed on a long term basis, and to remove the intended pollutants (phosphorus, sediment, stormwater volume, etc.).
Maintenance activities range in terms of the level of effort and expertise required to perform them. Routine maintenance, such as mowing and removing debris or trash, is needed multiple times each year. More significant maintenance, such as removing accumulated sediment, is needed less frequently, but requires more skilled labor and special equipment. Inspection and repair of critical structural features such as embankments and risers, needs to be performed by a qualified professional (e.g., structural engineer) that has experience in the construction, inspection, and repair of these features.
City Code 803.05 requires that all stormwater BMPs be maintained on a schedule, and that inspection information be available to the City, upon request.