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FLAG Deposition Subgroup Report

FLAG Deposition Subgroup Report Ellen Porter Air Quality Branch U.S. Fish and Wildlife Service Deposition Subgroup Included scientists and air quality specialists from FWS, NPS, and USDA-FS Report reviewed by deposition experts, both inside and outside of government

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FLAG Deposition Subgroup Report

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  1. FLAGDeposition Subgroup Report Ellen Porter Air Quality Branch U.S. Fish and Wildlife Service

  2. Deposition Subgroup • Included scientists and air quality specialists from FWS, NPS, and USDA-FS • Report reviewed by deposition experts, both inside and outside of government

  3. Subgroup focused on deposition of: • Sulfur (sulfate) • Nitrogen (nitrate, ammonium ion, nitric acid)

  4. FLAG Phase I • Summarization of currently available information on deposition and its effects on FLM areas • Recommendations for modeling and evaluating current and future deposition and its effects on AQRVs • Identification of information on critical loads and other levels of concern for AQRVs

  5. FLAG Phase II • Develop methods for establishing critical deposition loading values and levels of concern for FLM areas • Obtain additional information on deposition and deposition effects in FLM areas • Review previously established critical loads and levels of concern • Provide research and monitoring recommendations

  6. Ecosystem Effects of Sulfur and Nitrogen Deposition • Acidification of lakes, streams, and soils • Leaching of nutrients from soils • Injury to high-elevation spruce forests • Changes in nutrient cycling • Fertilization of terrestrial ecosystems • Eutrophication of estuarine and N-limited freshwater systems

  7. Critical Load: The concentration of air pollution above which a specific deleterious effect may occur. Concern threshold: An adverse impact threshold or other quantifiable level in resource condition or pollutant exposure identified by the FLM. • FLMs agree that a critical load or concern threshold value should: • protect the most sensitive AQRVs within each FLM area • be based on the best science available • ensure that no unacceptable change occurs to the resource

  8. Approaches to Establishing Critical Loads • National and regional workshops • Regional reviews • Site-specific studies

  9. Recommendations and Guidance for Evaluation Potential Effects from Increased Deposition • Includes: • the types of data, information, and analysis needed before a permit is considered complete • approaches and appropriate values for estimating wet and dry deposition • mitigation strategies NOTE: Applicant should consult with FLM to determine if a deposition impact analysis should be done

  10. Are there current adverse effects to AQRVs from deposition?Is the critical load exceeded? • If “yes,” FLM may recommend • stricter (than BACT) controls • emissions offsets • identification of sources contributing to adverse effects; SIP revision to reduce emissions from these sources • deposition and deposition effects monitoring/research in the FLM area • denial of permit

  11. Are there current adverse effects to AQRVs from deposition?Is the critical load exceeded? • If “no” or “unknown,” the FLM will ask: • will the new emissions cause or contribute to adverse effects or an exceedance of the critical load?

  12. Will the new emissions cause or contribute to adverse effects or an exceedance of the critical load? • If “yes,” FLM may recommend • stricter (than BACT) controls • emissions offsets • identification of sources contributing to adverse effects; SIP revision to reduce emissions from these sources • deposition and deposition effects monitoring/research in the FLM area • denial of permit • If “no,” FLM is unlikely to object to permit on basis of deposition effects • If “unknown,” FLM may recommend monitoring/research in the FLM area

  13. Information needed by FLM and applicant • Deposition-sensitive AQRVs • Critical loads or levels of concern • Current and future pollutant deposition rates in FLM area

  14. Deposition-sensitive AQRVs,Critical loads/Levels of Concern • Identified by FLMs • Information on many USDA-FS areas now on web; info on NPS and FWS areas on web in future • Web-based information can be updated as needed NOTE: Applicants should contact appropriate FLM before conducting analyses

  15. Web Information Examples: • USDA-FS information at www.fs.fed.us/r6/aq/natarm • Mt. Zirkel Wilderness (CO) • Concern thresholds for lakes with low ANC: • ANC change of > 1ueq/l, or • > 10% change in ANC over baseline • NPS web page under development • Mt. Rainier NP • Critical loads for lakes: • total sulfur: 3 kgS/ha/yr • total nitrogen: 5 kgN/ha/yr

  16. Current Deposition Rates in FLM Areas • See Table D-2 in Subgroup Report • Wet deposition: NADP data (on web) • Dry deposition: CASTNet data (on web) or assume “dry=wet” NOTE: Applicants should contact appropriate FLM before conducting analyses

  17. Future Deposition Rates in FLM Areas • Contributions from proposed source and sources permitted but not yet operating must be modeled in accordance with IWAQM recommendations • Future Deposition = Current + Proposed + Permitted (not yet operating) NOTE: Applicants should contact appropriate FLM before conducting analyses

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