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1.) EFED is recommending the following factors to identify target pesticides for inclusion in the study: extent of use area, environmental fate properties, and risk. Is this a reasonable strategy for selecting chemicals for the survey design?

  • Would some other approach better serve the long-term objective of developing and testing

predictive models?

2.) EFED is recommending that pesticide use area be the primary domain. In order to better define exposure levels to specific human populations and to better understand the processes affecting pesticide concentrations in surface source drinking water, it may be useful to use smaller domains. Such domains might be spatial or based on vulnerability criteria.

  • Should domains other than a pesticide's use area be used (regional domains, for example)?

  • What are the panel’s views on minimally acceptable data quality standards if the study had a larger number of domains.

  • Are there any suggestions for optimizing survey design to maximize the number of target pesticides represented while minimizing the total number of sampled CWSs without sacrificing data quality?

  • Could preferential selection of CWSs with source watersheds containing uses for multiple pesticides be incorporated into the design?

3.) EFED is considering stratifying the CWSs by vulnerability. The estimation of vulnerability would attempt to identify, for each pesticide and CWS, the likelihood of contamination. EFED would then randomly select CWSs from the vulnerability strata for inclusion in the survey.

  • How should we combine factors into an estimate of site vulnerability?

  • Would additional or different strata increase the usefulness of the data in addressing the objectives of the monitoring study?

  • What are the relative merits of using vulnerability-based as opposed to geographically-based stratification methods?

4.) EFED is proposing to use a geographic information systems (GIS) watershed characterization tool for identifying CWSs in the domains and strata.

  • Does the SAP agree with the usefulness of this tool for these purposes?

  • We are aware of limitations in the accuracy of the data used in the site selection tool. Is the panel aware of better ways of handling the accuracy and precision limitations of this data?

  • Is the Panel aware of alternative data sources that may not have these limitations?

5.) EFED recommends collecting raw water and finished water samples with reactive analysis of the finished water if pesticides are detected in the raw water. Finished water more directly reflects


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