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PREMISES FOR DEVELOPING AND APPLYING SEDIMENT QUALITY OBJECTIVES Presented and (mostly) agreed upon during the October 27, 2004 meeting of the Advisory Committee
BASIC GOAL OF SQO APPROACH • The primary goal is to determine if beneficial uses at a station are impaired • Assessment of larger areas and/or waterbodies is a secondary goal • The method for aggregating site-specific data for larger assessments may depend to some extent on the specific application (e.g., waterbody evaluation for 303d listing, dredging)
UNDERLYING PHILOSOPHY • At least two lines of evidence (or legs of the triad) are necessary to conclude a beneficial use is impaired • One line of evidence alone is too subject to error • Need to demonstrate both exposure and effect
TECHNICAL APPROACH • Develop quantitative scaling of indicator values • Avoid simple binary thresholds because: • Thresholds are uncertain and less responsive to degrees of change or difference • Scaled values are more useful for tracking trends • Scaled values produce more meaningful assessments
APPLICATION GUIDANCE • Challenge is to create a consistent MLOE application • Primary users will often be inexperienced engineers • BPJ not a realistic option Goal is to develop a “cookbook” that: • Addresses specific applications • Relates SQO to existing regulatory frameworks • Clearly states how SQO should NOT be used
BENEFICIAL USE PROTECTION CATEGORIES • Aquatic life (Infaunal) effects • Human health effects • Fish and wildlife effects
INDEPENDENT ASSESSMENT OF BENEFICIAL USES • MLOE will be used within each beneficial use, and independent assessments will be conducted for each • If any one beneficial use fails, the station fails, i.e., assessments are not additive across beneficial uses • However, the aquatic life use will probably take precedence because of state of knowledge and availability of data
GENERAL CONCERNS RELATED TO IMPLEMENTATION • Need strategies and guidance for working with imperfect information, e.g., “burden shifting” • Aggregating station-by-station assessments within context of specific regulatory frameworks • Constraints on use of SQO, i.e., what they are NOT suited for
SPECIFIC IMPLEMENTATION ISSUES • Station assessment • Chemistry that is not bioavailable • Imperfect information • Burden shifting mechanism • Incorporating other information • 303d listing guidance • # stations needed for system assessment • Toxic response but low chemistry and OK benthos • Data collection after listing
STATION: UNAVAILABLE CHEMICALS • Hard to define and demonstrate potential for impact • Would depend on plausible mechanism(s) • Possible long list of mechanisms • Station might never get clean bill of health • Margin of safety not clear if have elevated chemistry but OK toxicity and benthos • Establish burden shifting incentives that foster further investigation
STATION: IMPERFECT INFORMATION • Potential problems with data quality, recency, seasonality, conflicting requirements • Need minimum data requirements • Minimum list of chemicals to be measured • Use data less than 5 years old • BRI developed for summer; being assessed for other seasons • BRI requires surficial sediments; dredging requires deeper cores • Guidance must address all these issues
STATION: BURDEN SHIFTING MECHANISM • Value of incentives vs. rigid requirements • Acknowledgment of imperfect information, varied application scenarios • SQOs and related guidance should define several specific burden shifting mechanisms • What are thresholds for triggering burden shifting? • What is the time frame within which incentives play out?
INCORPORATING OTHER INFORMATION • Triad data may not always be definitive • Other data may be valuable in interpreting Triad results • Need to avoid potential for “dueling data” • Three Triad legs should trump other data for final decision making
303d LISTING APPLICATION • 303d guidance unclear about spatial distribution of samples needed for assessment • SQO guidance should somehow address this • Guidance should include incentives for further investigation when results equivocal • Questions re link between finding of impairment and identification of specific chemical cause • 303d and TMDL processes focus on specific causes • Link between SQO and 303d / TMDL desirable • Examine 303d / TMDL guidance for potential linkages