Outline of Sediment Quality Assessment and Control Strategies

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Proposed Topics For Sediment Quality Assessment

And Implementation Strategies

October 2, 2003

  1. Introduction

The purpose of this framework document is to present topics that should or could be addressed in the sediment quality objectives implementation policy under development. This document is to be used as a tool to focus dialogue on policy topics that could be considered during policy development. This document as written does not present proposed policy nor does it reflect direction or the opinion of SWRCB Management or Board Members.

  1. Definitions of key terms such as:

    1. Bays and Estuaries

    2. Sediment

Sediment is naturally occurring particulate material that has been transported to a body of water.

    1. Common Beneficial Uses (that could be affected by contaminated sediments)

  • Water Contact and Non-contact Recreation

  • Commercial and Sport Fishing

  • Aquaculture

  • Estuarine, Marine and Wildlife Habitat

  • Rare, Threatened or Endangered Species

  • Migration of Aquatic Organisms

  • Spawning, Reproduction and/or Early Development

  • Shellfish Harvesting

    1. Benthos

    2. Acute toxicity

Acute toxicity represents strong adverse effects (i.e., death or immobilization) resulting from a short-term exposure (usually ≤10 days for a sediment toxicity test).

    1. Chronic toxicity

Chronic toxicity represents a variety of lethal and sublethal adverse effects (e.g., mortality, reduced growth or reproduction, physiological changes) resulting from a long-term exposure.

  1. Conceptual model of sediment contaminant exposure and interactions

    1. Conceptual model

  • Figure showing pathways and processes important to the impact of contaminated sediment on ecological, human, and wildlife receptors

    1. Relationship of SQO project to the conceptual model:

  • A variety of processes within the sediment affect the bioavailability and toxicity of contaminants

  • Contaminant concentrations and processes within the surface active layer are of greatest importance

  • Sediment contamination impacts benthos through direct contact and ingestion

  • Sediment contamination impacts water column organisms through both direct contact and accumulation from the food web

  • Human and wildlife impacts from contaminants are primarily related to consumption on contaminated food

  1. Overview of Objectives

    1. Focus of Objectives

      1. Ecosystem components to be protected

        1. Sediment-dwelling organisms: numeric and narrative objectives

Numeric and narrative objectives will be developed to protect benthic communities for the following reasons (EPA, 2000):

  • benthic infauna are typically sedentary and therefore most likely to respond to local environmental impacts;

  • benthic infauna are important components of the food chain and often act to transport not only nutrients but also toxicants to the rest of the system;

  • monitoring benthic infauna provides an in situ measure of relative biotic integrity and habitat quality; and

  • benthic infauna have the strongest supporting database for effects in the field.

        1. Human health: narrative objectives

The California Water Code requires that the SWRCB develop SQOs that are protective of human health. Do to the complexity of relating sediment contaminant loading and potential human health affects and the resources required to develop state wide objectives the SWRCB will rely on narrative objectives and explore site specific tools. Tools such as food chain models and their ability to predict higher trophic level impacts reliably from contaminants in sediment will be evaluated.

        1. Fish and wildlife: narrative objectives (See

      1. Habitats/samples that they apply to:

        1. Bays, estuaries, surface sediments, subsurface sediments(?), etc.

      2. Habitats/situations that they don’t apply to:

        1. Suspended particles, effluent particles, offshore sediments, wetlands, nondepositional environments(?), freshwater sediments, etc.

    1. Narrative Objectives

      1. Purpose and characteristics of objectives

        1. Protect receptors not covered by numeric objectives

  • Fish, wildlife, and humans

        1. Provide tool to confirm designations derived from application of numeric objectives

  • Reduce uncertainty due to low-moderate concentrations

  • Incorporate site-specific factors

        1. Protect benthic resources when numeric objectives not appropriate (e.g., confounding sediment factors present)

  • Unusual forms or patterns of contamination

  • Unstable contaminant concentrations

        1. Management of chemicals for which numeric objectives are not available

      1. General description of how compliance with objectives will be evaluated

      2. Examples or list of proposed objectives

  • The concentration of chemical substances in enclosed bays and estuarine sediment shall not adversely impact beneficial uses,

  • The concentration of chemical substances in enclosed bays and estuarine sediment shall not increase to levels that would degrade aquatic life, and

        • The concentration of chemical substances in fish or other enclosed bays and estuarine resources used for human consumption shall not bioaccumulate from sediment into living resource to levels that are potentially harmful to human health.

    1. Numeric Objectives

      1. Purpose and characteristics of objectives

        1. Identify contamination levels protective of benthic macrofauna community

        2. Prioritize sites or chemicals of concern

  • Part of a weight of evidence evaluation

        1. Sediment screening objectives

  • Identify contamination levels associated with no adverse impacts

        1. Sediment management objectives

  • Identify contamination levels associated with some impacts

        1. Numeric values for individual chemicals or mixtures

  • Chemical-specific values if strong predictive association with effects is present

  • Mixture or summary values when association with effects is nonspecific

      1. Selection of chemicals or mixtures for objective development

        1. Identified concern (e.g., TMDL list)

        2. Demonstrated ability to predict absence/presence of impacts

      2. General description of how compliance with objectives will be evaluated

        1. May be different theoretical basis for different types of objectives (e.g., no impact vs. significant impact)

        2. May be different objectives for different habitats or regions (e.g., estuary vs. bay or by sediment type or region)

        3. Chemistry data from approved methods will be compared

  1. Methodology for Assessing Sediment Quality

  • Methods guidance for evaluating narrative objectives

  • Standardized and performance-based methods applicable to bays and estuaries

    1. Field sampling

    2. Sediment chemistry

    3. Sediment toxicity

    4. Laboratory bioaccumulation potential

    5. Benthic community impact

    6. Information management

  1. Application Summaries

    1. Evaluating Waterbodies for 303(d), 305(c ) Assessments

      1. General purpose of this activity

      2. Types of narrative/numeric objectives that apply

      3. Conceptual framework showing application of objectives in context of other activities and relationship to other programs

      4. Management/monitoring actions resulting from outcome of SQO application (e.g., impact designation or more data collection)

    2. Sediment Cleanup Actions

    3. Assessment of Dredge/Fill Material

    4. Monitoring Point Source Discharges

    5. Monitoring Nonpoint Source Discharges

  2. Regulatory Provisions

  3. Special Conditions

    1. Sediment Impact Zones

    2. Sediment Recovery Zones

  4. Review of Objectives

    1. Timing

    2. Process

    3. Factors considered (e.g., new data, new chem.-effect relationships, new laws)

Figure 1. Conceptual model of key processes for sediment-associated contaminants and routes of exposure for organisms.

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