Patricia Holden's Lab Integral to Wastewater Study

Setting a "floater" adrift

Bren Professor Plays Key Role in Coastal Wastewater Study

Bren Professor Patricia Holden, with Holden lab researchers Laurie Van De Werfhorst and Dr. Bram Sercu, as well as other collaborators from UCSB and other institutions, recently completed a two-year oceanographic and microbiological study of the coastal zone around the Montecito Sanitary District outfall. The project tracked how treated wastewater traveled after being discharged into the ocean off Butterfly Beach in Montecito.

Titled “Monitoring the Microbiology of the Montecito Outflow Wastewater Plume,” the report, filed with the State of California on Jan. 8, was funded by a $330,000 Proposition 50 grant awarded to Heal the Ocean from the State Water Resources Control Board (SWRCB). Work began in summer 2006 and was completed in November 2009.

According to the report's Executive Summary, "The overall objective of the project was to examine of the fate and transport of the treated effluent plume from a wastewater treatment plant (WWTP) discharging through a diffuser at the terminus of a short, shallow outfall. The project is important because its results are applicable to the many short outfalls discharging into California’s coastal waters."

“This is a novel project, newly combining very sensitive physical oceanographic and microbiological research approaches,” said Holden. “For the many short, shallow outfalls in California and elsewhere, we haven’t known before: do effluents travel towards shore, and if so, what do they carry?”

The project entailed a one-year weekly field sampling program that including boating to the end of the MSD outfall in the ocean across the street from the Four Seasons Biltmore Hotel and releasing GPS drifters to computer-map where the wastewater effluent plume traveled. The scientists would then track the drifters and collect samples along the paths they followed as they moved with the ocean currents. Continuous measurements of ocean waters were also made from a mooring near the outfall, and salinity depth profiles were measured with each drifter sampling.

UCSB oceanographers Professor Libe Washburn and Dr. Carter Ohlmann designed and oversaw the drifter deployments, tracked the plume movement, and collected the samples with assistance from Holden’s group. Holden and her laboratory team examined water samples for key DNA-based indicators of microbiological water quality, and measured nutrients, including nitrogen and phosphorus, with help from the Analytical Laboratory at the UCSB Marine Science Institute.

Scientists at USC examined samples for viruses, and the US Dept. of Energy's Lawrence Berkeley National Laboratory (LBNL) used an LBNL technique called the “PhyloChip” to further analyze DNA from Holden’s lab to identify all the bacteria in water samples.

Says Holden: “We learned that the effluent typically moves toward shore, and that it introduces nitrogen and phosphorus in the coastal zone, which apparently fertilizes the bacteria in the water.  Our mining of the PhyloChip data so far shows that there are some interesting bacteria in the effluent in common with the coastal zone. We look forward to understanding more about the latter, as it may indicate some subtle, and perhaps longer-term, influences of wastewater effluents in coastal zones.”


Read the full release from Heal the Ocean

Read the complete report

See the drifter data