Artificial substrate sampling, macroinvertebrates in a polluted reach of the Klamath River, Oregon.

Abstract

In 1964 the Federal Water Quality Administration (FWQA) initiated the Klamath Basin Study to determine the effects on water quality of agricultural wastes in irrigation return water on the Klamath and Lost rivers. As part of this study, macroinvertebrates were collected at monthly intervals to de termine the effects of irrigation return water and pollution from the city of Klamath Falls on the aquatic life. The advanced eutrophication of Upper Klamath Lake and the enrich ment of Klamath Kiver have been noted by several authors. Bonnell and Mote (1) reported the nuisance midge Chironomus utahensis attaining sum mer populations of 133,000/sq yd (111,000/sq m), and the alga Aphani zomenon forming mats with 20,000, 000 filaments/cu m. Needham and Needham (2) cited the Klamath River at Hornbrook, Calif., as an example of enormous productivity, with 1 sq ft (0.0920 sq m) of stream bottom yield ing 4,000 organisms and a standing crop of 5,000 lb/acre (5,600 kg/ha).