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