Zone 1:

Bounded on the west by the Continental Divide, north by the Colorado - Wyoming - Nebraska state line, east by Colorado - Nebraska state line, and south by an east/west line passing just north of Boulder.

Zone 2:

Bounded on the west by the Continental Divide, north by an east/west line passing just north of Boulder, east by the Colorado - Kansas state line, and south by an east/west line passing just north of Castle Rock.

Zone 3:

Bounded on the west by the Continental Divide (includes Monte Vista and Alamosa) north by an east/west line passing just south of the Fort Carson (includes Canon CIty and Salida) east by the Colorado - Kansas state line, and south by the Colorado - New Mexico state line.

Zone 4:

Bounded on the east by the Continental Divide (excludes Monte Vista and Alamosa), north by the Colorado - Wyoming state line, west by the Colorado - Utah state line, south by the Colorado - New Mexico state line.

Zone 5:

Bounded on the west by the Continental Divide, north by an east/west line passing north of Castle Rock, east by the Colorado - Kansas state line, and south by an east/west line passing just south of Fort Carson (excludes Canon City and Salida).