Students: Nora Hakkakzadeh, Daniela Hamann-Nazaroff, Mohammed Raouf Iqbal, Mike Kelly, Rita Wong, Miriam Urena, Hannah Wilchar, Jenny Kim

Client: Los Angeles Regional Water Quality Control Board

Advisor: Dr. Rebecca Shipe

Marine debris is a global problem that affects water quality, degrades beaches, and poses health problems to humans and aquatic organisms. The majority of marine debris is from land based sources due to human activities, such as littering and illegal dumping. Under the U.S. Clean Water Act, states must determine Total Maximum Daily Loads, or TMDLs, to calculate the maximum amount of pollutants that impaired waters can assimilate in order to meet water quality standards. The Clean Water Act Section 303(d) List of Water Quality Limited Segments for California includes Topanga Beach and Topanga Canyon Creek, but there have been no TMDL determined for either location. This paper aims to fill in the gap of information about the state of marine debris accumulation in the Topanga Canyon watershed in order to aid the Los Angeles Regional Water Quality Control Board (LARWQCB) in establishing a TMDL for the area. Our research consisted of collecting, quantifying, and categorizing anthropogenic debris in the upper creek, middle creek, mouth, and beach of the Topanga Canyon watershed according to the standard Rapid Trash Assessment (RTA) guidelines, and analyzing the debris by amount, weight, and type. In general, the coastal zones had a greater abundance of small pieces of debris whereas the creek zones had larger debris at a lower abundance. Plastic was found to be a persistent problem in all four regions, and Styrofoam was especially prevalent in the mouth and beach zones. Our research guided us towards several suggestions for the LARWQCB on how the problem of marine debris in the Topanga Canyon watershed can be managed and mitigated.