Figure
2-1

MEAN ANNUAL PRECIPITATION OF JKSYUS (IN INCHES)
SOURCE: Oregon State Water Resources Board, 1971, Pacific
Northwest River Basin Commission, 1970

Table 2-1

Under the Clean Air Act Amendments of 1970, Oregon has been divided into five Federal Air Quality Control Regions (AQCRs) on the basis of pollution concentrations, geography and economics. The JKSYUs lie within the Southwest Oregon AQCR and the Central Oregon AQCR (Figure 2-2).

In 1977, Crater Lake National Park (15 miles northeast of the planning area) was designated a mandatory Class I area by the Clean Air Act Amendments. Limits were set for sulfur dioxide and particulate levels in order to maintain air quality and visibility in this scenic area.

The airshed in the JKSYUs meets Federal and State Ambient Air Quality Standards, with the exception of the Bear Creek Valley. The topography and climatic conditions of this area restrict ventilation, making it one of the two areas in the continental United States most vulnerable to air pollution episodes.

In 1971-72, national air quality standards for particulates were exceeded at Medford, Grants Pass, and Ashland. By 1975, only the Bear Creek Valley exceeded the standards for particulates. This area was placed in an Air Quality Maintenance Area (AQMA). The Medford-Ashland AQMA has shown significant improvement, especially in particulate air quality, since 1970. Violations of secondary Federal standards (150 micrograms per cubic meter (ug/m3) for a 24-hour sample) dropped from 13 in 1970 to 7 in 1975. In 1976, violations increased to 25, but this increase was due mostly to unusual weather conditions and not to increased emissions (ODEQ 1976b). With the return of more normal weather conditions in 1977, the number of particulate violations dropped to nine (ODEQ 1977). While violations are becoming less frequent, the annual geometric mean for particulates has increased, showing a worsening trend in ambient air quality. At present, primary and secondary Federal standards (75 ug/m3 and 60ug/m3) are exceeded.

Carbon monoxide standards were violated 178 times in 1977, but insufficient data are available to determine the trend. Despite generally improving air quality, the Medford-Ashland AQMA was designated a non-attainment area by the U.S. EPA in 1978 because it failed to meet ambient air quality standards for suspended particulates and carbon monoxide.

About one-half of the particulates in the JKSYUs originated from the wood processing industries, slash burning, forest fires and wigwam waste burners. The main sources of excessive hydrocarbons appear to be veneer dryers, motor vehicles, general industry and activities related to gasoline marketing (ODEQ 1976a).

2.3 GEOLOGY AND TOPOGRAPHY

The JKSYUs encompass the Klamath Mountains, Western Cascades and High Cascades geographic provinces (Figure 2-3). They are bordered by the Basin and Range province to the east.