@

@

Dye study at Pacifica State Beach

January - April 2013 (During daytime on 3 separate days after rain. Exact dates TBD)

The third dye release was conducted on March 16, 2013 (Saturday) during 9 am - 11 am. Click here for photos.

The second dye release was conducted on March 7, 2013 (Thursday) during 8 am - 10 am. Click here for photos. or click here for a video.

The first dye release was conducted on February 9, 2013 (Saturday) during 11 am - 1 pm. Click here for photos.

A trial dye release was conducted on January 18, 2013 (Friday) Click here for photos.

The Civil and Environmental Engineering Department of Stanford University is conducting a dye tracer study at Pacifica to examine the transport of pathogens and pollutants from San Pedro Creek in the beach water of Pacifica State Beach. The research can also help us understand more about the transport of pollutants from other coastal streams in California.

Pacifica State Beach is a popular surfing spot. Discharging into the beach near its southern end is San Pedro Creek.  San Pedro Creek and Pacifica State Beach are listed on the Clean Water Act 303(d) list of impaired water bodies due to high indicator bacteria levels (e.g., total coliform, fecal coliform, enterococcus, and E. coli). Fecal indicator bacteria do not typically cause illness, but their concentrations indicate the presence of pathogenic organisms that are found in warm-blooded animal (e.g. human) waste. Pathogens pose potential health risks to people who recreate in contaminated waters. Previous research conducted by the Principal Investigator also detected Salmonella in San Pedro Creek, with a concentration of about 10 bacteria per liter of water. Salmonella is a zoonotic pathogen and is the leading cause of gastroenteritis worldwide.

@

As far as public health is concerned, it is important to assess and predict the concentrations of pathogens in the surf zone of the beach, where most surfers and swimmers come into contact with the beach water. When the creek discharges into the ocean, a portion of the discharge will be brought into the surf zone by the wave-induced littoral alongshore current, whereas the remaining portion will be transported out of the surf zone due to the initial momentum and buoyancy of the creek. The amount of pollutants from the creek entering the surf zone depends on a wide range of factors, including the discharge flow rate, the wave conditions, and the circulation in the bay. A specific goal of this project is to determine how much of the discharge from the creek enters the surf zone under the observed creek discharge and wave conditions.

@

The Principal Investigator of this project is Professor Alexandria Boehm at Stanford University. Her work focuses on understanding environmental and anthropogenic variables that influence the presence of pathogens and fecal indicator bacteria in bathing waters. 

@

More information related to this project can be found in the following:

@

@

@

@

@

@

@