Bacteria TMDL

The Marina del Rey Harbor has experienced high levels of bacteria in the Back Basins and Mother’s Beach portions of the harbor. A Total Maximum Daily Load (TMDL) for bacteria in the Marina del Rey Harbor Mother’s Beach and Back Basins became in effect in 2004. The TMDL is intended to limit the amount of bacteria entering the harbor from stormwater and urban runoff.

Potential sources of bacteria in the Harbor include dry-weather runoff and stormwater, as well as marina activities such as waste disposal from boats, boat deck and slip washing, swimmer “wash-off”, restaurant washouts and natural sources from birds, waterfowl and other wildlife. The County is trying mitigate the bacteria issue by implementing a number of best management practices intended to improve stormwater and urban runoff water quality. Projects include low flow diversions that divert urban runoff to sewers and installation of circulators under the dock at Marina Beach. Efforts are now being put into multi-pollutant and multi-beneficial approaches.

Examples of such best management practices and projects include:

  • Underwater Circulators, Educational Signage, and Bird Deterrents at Marina Beach
  • Filterra Bioretention Systems
  • Boone Olive Low Flow Diversion
  • Stormwater Diversion
  • Washington Blvd Low Flow Diversion
  • Oxford Basin Enhancement Project
  • Oxford Basin Low Flow Diversion
  • Parking Lot Retrofit Projects at Lots #5, #7 and #9 that utilize bio-filtration and bio-retention to treat and infiltrate runoff

The Parking Lot 5 project replaced planter boxes with four bio-filtration modular wetlands units as BMPs to treat the flow before being discharged into the Marina.

The Parking Lot 7 project installed six bioretention swales to infiltrate runoff from the 1 acre parking lot that used to discharge to the street and thereafter the Marina. The bioretention swales are located where the grass parkway used to be. The parkway has now transformed into a multi-benefit BMP that infiltrates runoff, improves water quality, benefits sustainability, and increases drought tolerant landscaping.

These two parking lots are the first of four parking lots that are planned to be retrofitted in the near future.

The Parking Lot 9 project includes 4 sets of bioswales and biofiltration units (similar to Parking Lot 5) that will treat the runoff before discharge into Basin E as well as multi-benefit amenities such as a parklet with benches and interpretive signage about how the BMP works.