INCORPORATING MULTIPLE LINES OF EVIDENCE INTO SEDIMENT QUALITY OBJECTIVES

1. INCORPORATING MULTIPLE LINES OF EVIDENCE INTO SEDIMENT QUALITY OBJECTIVES Stephen B. Weisberg Southern California Coastal Water Research Project

2. BACKGROUND • Multiple lines of evidence concept has been around for a while • Sediment triad is particularly well known • Has not yet found its way into sediment quality criteria • MLOE mostly used in site specific assessments • We are planning to recommend a MLOE approach • Both science advisory and stakeholder advisory panels have endorsed an MLOE approach • Challenge is creating a consistent MLOE application • Primary users will often be inexperienced engineers • Need a more rigorous structure than “Best Professional Judgment”

3. ISSUES • For what purpose will MLOE approach be used? • What are the end points (beneficial uses) of interest? • Which indicators will be used to address each MLOE end point? • How will these indicators be weighted in a scoring system ? • Will scoring be ordinal or binary?

4. PURPOSE • Primary purpose: To determine if beneficial uses at a station are impaired • Secondary: Programmatic applications of station criteria • Waterbody evaluation (303d listings) • Discharge compliance decisions • Local cleanup levels • Dredge material permitting • We can only provide guidance toward application process • Water code vs. site-specific decisions

5. ISSUES • For what purpose will MLOE approach be used? • What are the end points (beneficial uses) of interest? • Which indicators will be used to address each MLOE end point? • How will these indicators be weighted in a scoring system ? • Will scoring be ordinal or binary?

6. BENEFICIAL USE PROTECTION CATEGORIES • Aquatic life (Infaunal) effects • Human health effects • Fish and wildlife effects • MLOE will be used within each, but independent assessments will be conducted for each beneficial use

7. WHICH INDICATORS? • Infaunal effects • Sediment chemistry • Sediment toxicity • Benthic infaunal assemblage • Human health • Sediment chemistry • Fish/bivalve tissue chemistry • Fish/wildlife • Sediment chemistry • Tissue exposure • Biological effects

8. MLOE SCORING – INFAUNAL EFFECTS POSSIBLE FLAWS WITH RELIANCE ONINDIVIDUAL INDICATORS • Benthos • Physical disturbance (anchor, dredging) • Oxygen stress • Toxicity • Confounding factors (ammonia) • Agitation enhanced bioavailability • Chemistry • Paint chip • Tar ball • At least two legs of the triad are necessary to conclude impairment • Some scientific uncertainty associated with each leg • Need to demonstrate both exposure and effect

9. MLOE SCORING – INFAUNAL EFFECTS • At least two legs of the triad are necessary to conclude impairment • Some scientific uncertainty associated with each leg • Need to demonstrate both exposure and effect • Ordinal scoring • Both for individual indicators and for overall site assessment • Too much uncertainty to create binary thresholds • There is also a desire to prioritize among sites

10. TYPICAL TRIAD INTERPRETATION

11. SCORE EACH INDICATOR FROMZERO TO THREE 0 – Reference condition 1 – Slight deviation from reference (possibly defined by measurement error) 2 – Moderate effect 3 – Severe effect

12. EXAMPLE RESPONSE SCALES

13. OUTCOMES AT THE STATION LEVEL • Unimpaired (0 – 1 points) • Likely unimpaired (2 – 3 points) • Likely impaired (4 – 6 points) • Clearly impaired (7 – 9 points)

14. SOME EXAMPLES

15. DEVIL IS IN THE DETAILS • Scoring multiple metrics within an indicator class • e.g. Multiple toxicity tests at a site • e.g. Incorporating both empirical and EqP approaches • Less than three legs of the triad measured • Others you would like me to address?

16. MULTIPLE METRICS WITHIN A CLASS • Average score • Worst score • They each measure different things • Prioritizing among tests • Most sensitive test • Least sensitive test • “Best” test • Highest quality data • Some combination of frequency and severity

17. PROPOSED SCORING WHEN MULTIPLE METRICS ARE MEASURED

18. WHAT IF ONLY TWO LINES OF EVIDENCEARE AVAILABLE? • Looking for a combination of concordance and magnitude • Unimpaired: No effect from either indicator • Likely unimpaired: Small effect with no indicator, but no effect for the other • Unclear: Large effect with one indicator but no effect for the other • Likely impaired: Some effect for both indicators • Clearly impaired: High effect for both indicators

19. WHAT IF THERE IS ONLY ONE LINE OF EVIDENCE AVAILABLE? • Different circumstance than having three lines of evidence where only one shows an effect • Philosophy is still the same: Need demonstration of both exposure and effect • Want to avoid false positives • Classify stations that score a 3 as “Presumed bad” • Would revert to “likely impaired” if no new data are collected within three years • Want to guard against false negatives

20. MOVING FROM STATION ASSESSMENT TO SYSTEM ASSESSMENT: 303d EXAMPLE • Impairment of a station does not equate to system impairment • Probably few (no?) systems without some anthropogenic impairment • There is assessment uncertainty at the station level • Measurement variability • Assessment tool error • Present State Board approach defines impairment relative to frequency of station/sample exceedances in waterbodies with the least human influence • That approach can work well here

21. ESTABLISHING FREQUENCY THREHOLD FOR DEFINING SYSTEM IMPAIRMENT • Identify systems (or subsystems) that are least influenced • Use project data base to create a frequency plot • Select a frequency threshold based on the plot • Might also use site replicability information • Might also incorporate a magnitude component to the threshold

22. ESTABLISHING FREQUENCY THREHOLD FOR DEFINING SYSTEM IMPAIRMENT • Identify systems (or subsystems) that are least influenced • Use project data base to create a frequency plot • Select a frequency threshold based on the plot • Might also use site replicability information • Might also incorporate a magnitude component to the threshold • Particularly need your input at this stage • Defining reference systems • Interpreting frequency plot • Determining need for habitat specific thresholds

23. SOME 303D DEVIL IN THE DETAILS • How many stations are necessary to classify a waterbody? • What if stations are non-random and non-representative of the system?

24. SOME 303d DEVIL IN THE DETAILS • How many stations are necessary to classify a waterbody? • What if stations are non-random and non-representative of the system? • We will need to provide guidance on such issues

25. 303d PRODUCT FROM THIS PROJECT • Prepare approximately three pages of text with recommended approach • Point out consistency with State Board approach for other stressors • Includes graphics that describe analytical results • Frequency plot from reference sites • Station repeatability information • Ultimate 303d decisions made by other individuals • So far, they find this approach agreeable

26. HUMAN HEALTH • Both legs (tissue chemistry, sediment chemistry) necessary to conclude impairment • Linkage between exposure and effects even more necessary than for benthic effects • Tissue chemistry thresholds are straightforward • State has fishery closure levels • Sediment chemistry thresholds are less clear • Will likely differ from infaunal effects thresholds • We are exploring both empirical and mechanistic models

27. SPECIAL ISSUES – HUMAN HEALTH • Can we do a station assessment? • Exposure will generally be system-specific rather than station-specific • Are all species acceptable? • Resident vs. migratory • Indicator vs. human consumed species

28. FISH / WILDLIFE EFFECTS • Will probably require three lines of evidence as necessary to conclude impairment • Sediment chemistry, tissue chemistry, biological effects • Greater physical dislocation between sediment and effect • Thresholds for each line are less well developed than for other modes of effect • Mechanistic modeling becomes increasingly important • Also increasingly difficult • Least amount of data • Most applications will need to be based on first two modes of effect • Our goal is to develop framework for the future

29. TIMELINE • Draft sediment quality objectives due August 2005 • Workplans for individual indicator elements already prepared and studies begun • We will prepare a MLOE integration workplan following this meeting • We will ask the Scientific Steering Committee to review it next • Looking for your input today

30. MLOE GLOSSARY

31. SOME TOUGHER CASES