(Adopted Oct. 5, 1979)(Amended March 7, 1980)(Amended Sept. 10, 1982)(Amended July 12, 1985)(Amended August 1, 1986)(Amended June 28, 1990)(Amended May 3, 1991)(Amended December 7, 1995)(Amended May 10, 1996)(Amended October 20, 2000)


(a) The modeling analysis performed by the applicant shall consider:

(1) the net emission increase from the new or modified source; and

(2) the location of the source and its distance to the closest boundary of specified Federal Class I area(s).

(b) Level 1 and 2 screening analysis for adverse plume impact pursuant to subparagraph (b)(5)(C) of this rule for modeling analysis of plume visibility shall consider the following applicable screening background visual ranges:


Federal Class I Area Screening Background
Visual Range (km)
Agua Tibia 171
Cucamonga 171
Joshua Tree 180
San Gabriel 175
San Gorgonio 192
San Jacinto 171


For level 1 and 2 screening analysis, no adverse plume impact on visibility results when the total color contrast value (Delta-E) is 2.0 or less and the plume contrast value (C) is 0.05 or less. If these values are exceeded, the Executive Officer shall require additional modeling. For level 3 analysis the appropriate background visual range, in consultation with the Executive Officer, shall be used. The Executive Officer may determine that there is no adverse visibility impact based on substantial evidence provided by the project applicant.

(c) When more detailed modeling is required to determine the project’s visibility impact or when an air quality model specified in the Guidelines below is deemed inappropriate by the Executive Officer for a specific source-receptor application, the model may be modified or another model substituted with prior written approval by the Executive Officer, in consultation with the federal Environmental Protection Agency and the Federal Land Managers.

(d) The modeling analysis for plume visibility required pursuant to subparagraph (b)(5)(C) of this rule shall comply with the most recent version of:

(1) “Guideline on Air Quality Model (Revised)” (1986), supplement A (1987), supplement B (1993) and supplement C (1994), EPA-450/2-78-027R, US EPA, Office of Air Quality Planning and Standards Research Triangle Park, NC 27711; and

(2) “Workbook for Plume Visual Impact Screening and Analysis (Revised),” EPA-454-/R-92-023, US EPA, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711;

(3) “User’s Manual for the Plume Visibility Model (PLUVUE II) (Revised),” EPA-454/B-92-008, US EPA, Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711 (for Level-3 Visibility Analysis)

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