High-tech armada monitors urban wastewater
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 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.
This portion of the environmental monitoring effort is being led by USC and funded by the National Oceanic and Atmospheric Administration. The team will deploy 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, with the results accessible at 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 David Caron, professor of marine environmental biology at the USC Dornsife College of Letters, Arts and Sciences.
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, a natural part of marine environment, 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 the 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.
Repairs to the OCSD pipeline began on Sept. 11, when the agency switched 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.
Led by USC in partnership with the Southern California Coastal Ocean Observing System and OCSD, the research team includes scientists from the University of California, Irvine, the University of California, Los Angeles, the University of California, Santa Cruz, the University of California, Santa Barbara, the Scripps Institutution of Oceanography, the Southern California Coastal Water Research Project, the Monterey Bay Aquarium Research Institute, Moss Landing Marine Laboratories and Liquid Robotics Inc.