|
FAQ: Updated SQuiRT Cards
Q: What changes were made to AETs?
A: In December 1998 and again in June of 1999, Washington State issued draft, interim revisions to the Sediment Management Standards Rule, which included the addition of a new bioassay endpoint to the suite of confirmatory biological effects tests: a 20-day growth test using the juvenile polychaete Neanthes arenaceodentata. This endpoint lowered the lowest AET, the value reported on the SQuiRTs, for many contaminants.
Q: Why are the values interim?
A: The values reported represent preliminary values pending completion of additional technical work on individual AET values, reliability analyses, and discussions with other involved agencies. Washington State is still resolving some statistical issues of data analysis and classification of bioassay results.
Q: Will the final AETs be different?
A: Since AET values are essentially determined by a single result (i.e., the highest non-toxic sample) as opposed to the entire distribution of results (e.g., as with a TEL or PEL), the final AET values used by the state may vary substantially depending on the outcome of their analyses.
Q: What are Water Quality Criteria?
A: Section 304(a)(1) of the Clean Water Act requires EPA to develop criteria for water quality that accurately reflect the latest scientific knowledge. These criteria are based solely on data and scientific judgments on pollutant concentrations and environmental or human health effects. Section 304(a) also provides guidance to states and tribes in adopting water quality standards. Criteria are developed for the protection of aquatic life as well as for human health; the SQuiRT cards deal only with the aquatic life values.
Q: What is the latest compilation?
A: From time to time, EPA revises their compilation to keep states and tribes informed about the most current recommended water quality criteria. EPA published the agency's current recommended 304(a) criteria by Federal Register notice, which first appeared on December 7, 1998 (Vol. 63 No. 234). Subsequent re-publications have clarified some textual matters, but the basic numerical criteria remained the same until changes in May 2005.
Q: What is the status of existing criteria while they are under revision?
A: Water Quality Criteria published by EPA remain the agency's recommended criteria until EPA revises or withdraws them. EPA has consistently upheld the use of the current criteria and considers them to be scientifically sound until new, peer-reviewed scientific assessments indicate changes are needed.
Q: What changes were made in the latest compilation?
A: There were many individual updates made in the latest compilation. However, many of the updates result from a few basic changes. These include expansion of available data through initiatives such as the National Toxics Rule, the California Toxics Rule, and Great Lakes Initiative Guidelines; expression of criteria for metals in terms of dissolved metal in the water column; and changes in the form of chemicals or valence state of metals for which criteria are published.
Q: How do the SQuiRT cards deal with old and new criteria?
A: For metals' Ambient Water Quality Criteria (page 3), some changes are noted on the SQuiRTs in notations connected with the values. The SQuiRT cards have just been updated with the most recent values for cadmium, copper, and tin. The SQuiRT for Organics (pages 5-8) lists just the new values and does not attempt to indicate where changes have been made.
Other pages in this series
|
|
|
|
