September - October 1992:
High enterococcus bacteria counts detected during a reconnaissance survey in 1991 indicated a possible public health risk in the lower Columbia River. The purpose of this project was to determine if a chronic public health risk exists during high contact recreation periods due to bacteria contamination. Ecology sampled twelve stations between the mouth of the Columbia River and river mile 170 (Hood River) weekly- from September 1 to October 12, 1992. Fecalcoliform and enterococcus bacteria were monitored, as well as oxygen, temperature, pH, and conductivity. Water quality standards for temperature, pH, and percent oxygen saturation were exceeded at several stations. Fecal coliform bacteria standards were exceeded at two stations (llwaco Marina and Sauvie Island), but a chronic public health risk is not indicated. Enterococcus bacteria did not exceed standards.
November - December 1992:
The geometric mean of fecal coliform counts collected between November 22 and December 28, 1992, exceeded water quality standards at two sites on the lower Columbia River: Jiwaco Marina (Washington State marine standard) and near Longview, Washington (Washington State freshwater standard). Fecal coliform counts were also high at Sauvie Island, Oregon, but did not exceed Oregon State freshwater standards (Oregon fecal coliform standards are higher than Washington standards). The geometric mean of enterococcus bacteria counts exceeded freshwater standards at Sauvie Island and were high at Longview, Washington. -One enterococcus bacteria sample at Sauvie Island exceeded the federal 'single sample not to exceed' standard during this study.
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