Water Quality: Temperature to Toxics, Boise Cascade Pulp and Paper Mill, 1990 Environmental Conference Proceedings

Boise Cascade Corporation operates a kraft pulp and paper mill at Wallula, WA. Treated effluent is discharged to the Columbia River through a new submerged outfall into the Lake Wallula reach upstream from McNary Dam. The new outfall was completed in early 1989 to maintain compliance with Washington WQS criteria for temperature and dissolved oxygen (DO) beyond the authorized dilution zone in the receiving water. This paper reviews the water quality design basis for achieving compliance, and compares this to results of followup field sampling to demonstrate compliance during a late summer period of expected low natural water quality. The field results showed that the new outfall achieved compliance with temperature and DO WQS criteria. Also presented are results of an evaluation comparing estimated effluent concentrations at the dilution zone boundary with new Washington Water Quality Standards criteria for toxic substances. These results indicate that the new outfall will comply with toxic substances criteria.