Research Areas > Regional Monitoring > Historic Reference Surveys

Project: Historic Reference Surveys: 1977-1990

SCCWRP Research

In 1969, managers from several large southern California Publicly Owned Treatment Works (POTWs) were investigating ways to monitor the effects of their wastewater discharge. This was part of the impetus behind SCCWRP's formation. In the years that followed, SCCWRP became extensively involved in the development and implementation of monitoring efforts to assess the effects of the wastewater discharge from these POTWs. Initially, individual POTW monitoring programs primarily surveyed sites near the end of their discharge pipes (outfall areas) and the effects of wastewater on marine life in those areas. Data from these surveys were sent to SCCWRP, where the information was compiled and compared with other POTW discharge sites. Recognizing that comparable information from non-outfall areas was limited, SCCWRP initiated three reference condition surveys designed to identify possible control (or reference) sites for comparison to outfall conditions. These surveys also provided a means to assess changes in reference conditions and regional variability over time relative to changes occurring at outfall sites.

1977 60-Meter Control Survey

The 1977 60-meter Control Survey was conducted off the mainland shelf of southern California from Point Conception, California to the United States-Mexico border. The goal of the survey was to identify possible control areas for contrasting natural conditions with conditions at municipal wastewater discharge sites, and to define normal variations in the chemistry and biology of sediments on the mainland shelf. The survey assessed sediment chemistry, infauna, and trawl-caught fish and invertebrate populations. As a result of the survey, 71 sites were sampled for a single depth (60 m), and, of these, 29 locations were identified that could be used as controlled or reference conditions.

• Data and report from 1977 Reference Survey

1985 Reference Site Survey

The 1985 Reference Site Survey resampled some of the 1977 60-m survey sites to determine if changes had occurred in the past 10 years, and also expanded the range of sampling depths. The goal of the 1985 Reference Site Survey was to provide information on environmental conditions from the least contaminated areas on the southern California mainland shelf, and to evaluate changes in conditions at these sites from those reported in the 1977 survey. In the survey, 13 of 71 sites sampled in the 1977 survey were resampled, while additional reference sites were established at 30 and 150 m depths in each area, resulting in sampling of 38 reference sites. The survey assessed sediment chemistry, infaunal and trawl-caught fish and invertebrate populations, and bioaccumulation of contaminants in fish and invertebrate tissue.

• Data and report from 1985 Reference Survey

1990 Reference Site Survey

As with the 1977 and 1985 reference site surveys, the 1990 Reference Site Survey sampled sites along the mainland shelf of southern California to provide reference information for comparison to data collected from sites near wastewater discharges. A second goal of the study was to update information collected in the 1977 and 1985 surveys and describe changes that had occurred since the previous surveys. The 1990 survey was similar to the 1985 survey in that depths of 30, 60, and 150 meters were sampled. In all, a total of 20 sites were sampled from Point Mugu to the United States-Mexico border. The survey assessed sediment chemistry, infauna, trawl-caught fish and invertebrate populations, and bioaccumulation of contaminants in fish and invertebrate tissue. Comparison of reference assemblages among the three surveys showed that numbers of species, abundance, and biomass of fishes and invertebrates was generally lowest in 1985, perhaps reflecting effects of the 1982-83 El Niño. Assemblages were more similar in 1977 and 1990.

• Data and report from 1990 Reference Survey