Environmental Monitoring

A multi-institutional team of scientists and engineers will field a small navy of research vessels and sensors this month to monitor water quality when the Orange County Sanitation District (OCSD) temporarily switches pipelines for treated urban wastewater.

The planned month-long infrastructure repairs to the existing OCSD pipeline are a rare opportunity for scientists to closely track what happens in the coastal ecosystem when a new source of water is introduced — and they’re opening the data to the public, in near real-time.

Led by USC Dornsife and funded by the National Oceanic and Atmospheric Administration, this portion of the environmental monitoring involves deploying four robotic submarine gliders, two large sensor moorings, water samplers, an Environmental Sample Processor and sample from at least two research vessels for continuous monitoring at the temporary discharge site and in and around the plume emanating from the pipe. The results will be accessible at www.sccoos.org/projects/ocsd-diversion.

“The OCSD has done a fantastic job of bringing a wide spectrum of local talent and cutting-edge technology to bear on monitoring any potential impacts the discharge might have on coastal waters,” said Dave Caron, professor of marine environmental biology in USC Dornsife.

Though the urban wastewater from Orange County is cleaned and highly treated, it is more nutrient-rich than the coastal waters into which it is released. That influx of nutrients, including phosphorus and nitrogen, has the potential to affect the food web off the coast, potentially triggering algal blooms, Caron said.

Algal blooms are a natural part of marine environment and have been on the rise off of California’s coast over the past 10 years. Though many are harmless, some produce toxic chemicals that are introduced to the food chain. In addition, the subsequent decay of algae can rapidly deoxygenate water in an area, adversely affecting other aquatic life. The purpose of this study is to determine if treated wastewater intensifies this algal bloom response.

The researchers plan to track any algal blooms that occur, first spotting them with the stationary monitoring equipment and then following up with gliders and boats. The data gathered will also help researchers more quickly assess immediate potential impacts to the environment or public health.

During repairs to the OCSD pipeline, the agency is switching to a temporary pipeline that discharges about a mile offshore. The current OCSD pipeline discharges about five miles offshore.

In addition to the National Oceanic and Atmospheric Administration’s Ecology and Oceanography of Harmful Blooms Program, additional funding for the project comes from the National Science Foundation and the OCSD.

The research is led by USC Dornsife in partnership with the Southern California Coastal Ocean Observing System (SCCOOS) and OCSD, and includes scientists from UC Irvine, UCLA, UC Santa Cruz, UC Santa Barbara, Scripps Institute of Oceanography, Southern California Coastal Water Research Project, Monterey Bay Aquarium Research Institute, Moss Landing Marine Laboratories and Liquid Robotics Inc.

The Southern California Coastal Ocean Observing System has created a webpage that provides data from the continuous ocean monitoring that is open and available to the public. Visit www.sccoos.org/projects/ocsd-diversion for more information.