Stormwater Compliance

Stormwater Compliance

The City of San Dimas has two drainage systems, (1) the sewers and (2) the storm drains. The storm drain system was designed to prevent flooding by carrying excess rainwater away from city streets out to the San Gabriel River and finally, out to the ocean. During storms in urban areas, rainwater runoff carries pollutants generated from commercial businesses, residential areas, streets, and sidewalks, directly to the ocean, creating stormwater pollution. Materials such as sediment, paint, plaster, yard waste, used motor oil, animal waste, and trash contain chemicals, nutrients, and bacteria that are harmful to aquatic life and humans.

Stormwater and Water Quality Inspections 

How You Can Make a Difference 

To prevent stormwater pollution, follow these simple tips:

• Never pour household hazardous waste materials down the drain, onto sidewalks or into catch basins. Take these materials to a hazardous waste materials collection center or round-up event. For the next Household Hazardous Waste (HHW) Round-up event, visit https://cleanla.lacounty.gov/events/
• Use pesticides, herbicides, and fertilizers according to the label instructions. Remember not to apply them before rain and avoid overwatering your plants or lawn.
• When walking your pets, remember to pick up your animal's waste and dispose of it in a trash can.
• Never put motor oil in the trash or pour it on the ground or down a storm drain. Used oil should be properly stored and taken to a local collection center (AutoZone or Tire Choice Auto Centers) or a hazardous waste round up event.
• If you're using latex-water-based paints, you can wash your paintbrushes directly in your kitchen or bathroom sink. Don't rinse your brushes into the street.
• If you use oil-based paints, clean them by rinsing brushes with solvent in a container. Take the unused liquid and residue to an HHW collection event. For the next Household Hazardous Waste Round-up, visit the Los Angeles County Public Works website.

Illegal disposal of any material other than stormwater in the storm drain system is a violation of the National Pollutant Discharge Elimination System (NPDES) Permit (Section 402 of the Federal Clean Water Act). Violators and cities can be subject to serious financial penalties in excess of $10,000 per day.  Call the City of San Dimas Public Works Department at (909) 394-6240 or Los Angeles County Department of Public Works at 888-CLEAN LA (888-253-2652) for more information on stormwater pollution prevention or to report illegal dumping.

Annual Stormwater Reports

The City tracks the implementation of stormwater compliance measures through the Annual Report process. Data is collected by the city throughout the year and reported to the Los Angeles Regional Quality Control Board each December. Annual Reports are available for review at the Los Angeles Regional Water Quality Control Board office in downtown LA or online on the California Water Boards website.

Resources

Best Management Practices for Construction Sites & Tenant Improvement Projects
Los Angeles County Low Impact Development (LID) Standards Manual 

Best Management Practices for Mobile Businesses

Automobile Detailers 
Carpet Cleaners
Cement Mixing and Masonry 
Painting Services
Pet Services
Pressure Washing
Sanitary Toilet Servicing (Portable Restrooms) 

Stormwater Quality and Regulations

Water quality is a growing concern in communities throughout the country and municipalities including San Dimas are focusing on stormwater runoff as one approach to address this concern. Stormwater runoff results from rain or melting snow in some areas that are not absorbed into the ground. Runoff is also generated outside of the “rainy season” by nuisance water resulting from activities such as over-watering lawns, vehicle washing, or draining of swimming pools and other water features. This excess water carries trash, motor oil, fertilizers, pet waste, and other contaminants directly to our lakes, streams, and beaches untreated. Excess contaminants dumped into our environment and the depletion of our valuable water resources negatively affect the entire community. Many cities like San Dimas will be at risk of serious fiscal impacts, including fines (could be up to $10,000 per day per violation), costly retrofit projects, and repairs if the stormwater quality is not properly addressed. Federal regulations such as the National Pollutant Discharge Elimination System (NPDES) Permit are a catalyst for San Dimas to create storm-water quality programs.

Watershed Control Measure Milestone Progress

In 2015, the Cities of Claremont, La Verne, Pomona, and San Dimas, collectively referred to as the East San Gabriel Valley Watershed Management Group (the Group), developed a Watershed Management Program (WMP) to fulfill the requirements of the National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit No. R4-2012-0175 (2012 Permit). The original WMP established the scheduling of Best Management Practices (BMPs) by applying percent milestones from the San Gabriel River and Impaired Tributaries Metals and Selenium TMDL (Metals TMDL) to the runoff volume from the 85th-percentile storm. For example, the Metals TMDL requires 35% compliance in 2020 for lead in wet weather and the 2015 WMP proposed capturing 35% of runoff from the 85th-percentile storm by 2020. While the compliance pathway chosen in the 2015 WMP was to capture runoff from the 85th percentile storm, the actual required reductions and volume of stormwater capture were uncertain due to the limited availability of water quality data within the Group’s WMP area. The Group acknowledged that monitoring data collected through implementing the Coordinated Integrated Monitoring Program would allow a more refined assessment of the receiving water quality in the Group’s WMP area. Therefore, the assessment to track progress on Watershed Control Measure requirements was evaluated by measuring the percent compliance of water quality samples compared to the water quality objectives. For example, in 2020, 35% of wet weather data collected for a given constituent (except E. coli) were to be in compliance with water quality objectives. (E. coli was analyzed differently, as it has an established Total Maximum Daily Load (TMDL) with final deadlines of 6/30/2026 for dry weather and 6/30/2036 for wet weather.)