November 9, 1988







MEMORANDUM

SUBJECT:  Request for Use of ISC 6.2

FROM:     Dean A. Wilson, Meteorologist
          Techniques Evaluation Section, SRAB (MD-14)

TO:       James W. Yarbrough, Air Modeling Contact
          Region VI (6T-AN)


     In response to your request, the Model Clearinghouse concurs
with  your position that Change 2 of the ISC model in UNAMAP 6
may be used for the five PSD analyses referenced in your memoran-
dum of November 3, 1988.  However, we also recommend that you
review the status of these permits when the necessary corrections
to ISC have been completed and are available.  If, at that point
in time, the analyses are not substantially underway, then these
sources should be modeled with the corrected version of ISC.

     If you have any questions please contact me.

cc:  D. deRoeck (MD-15)
     S. Reinders (MD-14)
     Regional Modeling Contact, Regions I-V, VII-X (with incoming
       memorandum and list of the FY-89 Clearinghouse Memoranda)