January 3, 2002

N3615 (2350)

Mr. S. William Becker Executive Director STAPPA /ALAPCO 444 North Capitol St. NW Washington, D.C. 20001

Dear Mr. Becker:

The National Park Service (NPS) and U.S. Fish and Wildlife Service (FWS) have developed a Deposition Analysis Threshold ( DAT) for sulfur deposition within NPS and FWS Class I air quality areas. The DAT for sulfur follows the development of a DAT for nitrogen, which was presented in an August 1, 2001, letter to you. Both DATs were developed in response to requests by permitting authorities and permit applicants to develop consistent, predictable permit reviewprocesses. Through this letter and the enclosed guidance document, we seek to in form you of this refinement in our permit review process. The nitrogen and sulfur DATs will also be used in reviewing National Environmental Policy Act and other relevant documents. We would appreciate your sharing this document with your members so that they can incorpor ate the use of these DATs into state and local planning, gu idance, and permit review processes.

The final Federal Land Manager’s Air Qu ality Related Values Work Group (FLAG) report states that State agencies and othe rs who intend to use the FLAG information “deserve further guidance and implementati on assistance, provided through established formal and informal links between FLMs, St ates, EPA, and others.” (page 151). This DAT and guidance document are a conti nuation of this ongoing commitment. By developing DATs, the NPS and FWS seek to improve the review pr ocess by providing a quantitative value with which to evaluate ni trogen and sulfur deposit ion in Class I areas. By providing applicants, permitting authoritie s, and the FLMs with a specific value with which to evaluate potential impacts, we believ e that the use of DATs will help to expedite the permit review process when NPS and FWS Class I areas are involved. The U.S. Forest Service (USFS), a collaborator in the FLAG process, currently uses separate deposition thresholds, and the DATs may not apply to USFS Class I air quality areas.

Enclosed please find a copy of Guidance on Deposition Analysis Thresholds . This document discusses both the nitrogen DAT as well as the new sulfur DAT. We are providing this single guidance document so that interested parties will have a clear understanding of the DAT development proce ss and how it will be utilized by the NPS and FWS. This document will also be made available at the following web addresses: http://www.aqd.nps.gov/ard/flagfree http://www.aqd.nps. gov/ard/whnew.htm2

Please notify your member states, local agencies , and other interested parties as to the availability of this document. We understand that it may take some time to incorporate this guidance into the permit review process.

We would welcome any questions that you may have regarding the DATs or guidance document. Please contact Don Codding ( 303-969-2076) or Tamara Blett (303-969-2011) of the NPS, or Ellen Porter of the FWS at (303) 969-2617.

Sincerely, Sincerely,

Christine L. Shaver Sandra V. Silva Chief, Air Resources Division Chief, Air Quality Branch National Park Service U.S. Fish and Wildlife Service

Enclosure

cc: Bob Hodanbosi STAPPA Permitting Committee Chair c/o Ohio Environmental Protection Agency Division of Air Pollution Control P.O. Box 1049 Columbus, OH 43216-1049

WESTAR Council 1001 Southwest Fifth Ave., Suite 1100 Portland, OR 97204-1127

NESCAUM 129 Portland St., Suite 501 Boston, MA 02114

bcc: Regional and Park Air Resource Coordinators ARD: All Staff, Reading and Project File ARD: Dcodding:dc:01/03/02:2076:SDAT-STAPPA.ltr