Opinion ID: 187435
Heading Depth: 3
Heading Rank: 2

Heading: First Factor:.EPA Region 1's Use of a Bright-line Test

Text: As explained in greater detail in Part VI, EPA Region 1 used a bright-line test to determine which counties within a C/MSA would be designated as attainment. The test worked like this: EPA Region 1 ranked each of its counties from highest to lowest according to their weighted emissions scores. Starting from the top of the list, EPA Region 1 added each county's score and stopped when the sum hit 80%. Counties above the 80% cut-off point were presumed to be nonattainment; those below were designated as attainment, provided they did not have a violating monitor and were not among those recommended for nonattainment status by a state. See Technical Support Document § 6.1.1 (Factor 1). State petitioners argue that application of this 80% test led to inconsistent area designations, and they are right in one instance. Rockland County, New York, which is not in EPA Region 1 and was designated as nonattainment, would have been designated as attainment under the 80% test. Such an inconsistency is evidence of an arbitrary designation, but as Part VI explains, EPA's mistaken designation of Rockland County is an aberration, and petitioners fail to identify any other designation that might have changed had EPA applied the 80% test elsewhere. Nothing about the way EPA Region 1 applied the first factor reveals a fundamental problem with EPA's evaluation of emissions in potentially contributing areas.