Sediment Quality Research Plan

View SCCWRP’s full thematic Research Plan for Sediment Quality (PDF)

2020-2021 Executive Summary

The quality of sediment that underlies water bodies is a sentinel indicator of the health of marine ecosystems. Pollutants discharged from wastewater treatment plants and urban watersheds have led to sediment contamination along California’s coastline, with contamination levels most acute in bays and estuaries, where slower-flowing waters promote settling of contaminant-laden particles. Humans and most wildlife will rarely come into direct contact with this sediment, but organisms like burrowing worms and crustaceans spend their entire lives here – and these organisms form the base of food webs that extend all the way to humans. Since the 1970s, SCCWRP has been a leader in helping Southern California environmental managers understand and remediate the ecosystem impacts of sediment contamination. SCCWRP is working to understand how sediment-based chemical contamination is transferred through food webs and how it can adversely impact wildlife and humans. SCCWRP’s goal is to better position California’s environmental management community to direct resources optimally to mitigate ecosystem damage. In California, this work has culminated with State Water Board adoption of paired sediment quality assessment frameworks defining for environmental managers how to assess compliance with California’s Sediment Quality Objectives in enclosed bays and estuaries.

SCCWRP’s research falls into the two main categories that reflect the two main routes by which organisms become exposed to sediment contamination: (1) direct exposure, where bottom-dwelling marine life come into contact with and/or ingests contamination in sediment, and (2) indirect exposure, where predators accumulate toxins in their bodies as they consume contaminated prey. Given SCCWRP’s progress, researchers are transitioning to expansion and refinements of assessment frameworks, building tools that promote usability and applicability,, and enhancing toxicity testing infrastructure.

This year, SCCWRP is continuing to assist environmental managers in translating water and sediment quality objectives into application. SCCWRP’s focus for 2020-21 will be on:

  • Guidance for site-specific threshold development: SCCWRP is working to develop guidance for establishing site-specific objectives that can support environmental assessments for compliance-oriented programs. Although regulatory agencies have established processes for dischargers to develop site-specific objectives when water-quality objectives are not applicable to a site, the processes are often not straightforward, and existing guidance can be limited, creating inconsistencies and variation in how site-specific objectives have been established. SCCWRP is working to develop scientifically robust and publicly transparent frameworks that can guide managers in developing site-specific thresholds to protect aquatic life and other beneficial uses.
  • Optimizing toxicity testing protocols: SCCWRP is working to increase consistency, confidence and comparability of the Ceriodaphnia dubia chronic reproduction test, which is widely used in toxicity assessments. Despite its long history of use in compliance-based monitoring, the C. dubia test has been subject to culture crashes, sometimes inexplicable variability, and seemingly random toxic responses to negative controls. SCCWRP will investigate the test conditions and factors that can be controlled, and then develop quality assurance and quality control guidance to ensure labs can produce comparable, high-quality test results. The ultimate goal is to ensure management decisions based upon this toxicity test can be made with confidence.