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Pennington, A.T., A.K. Harding, C.W. Hendricks, and H.M.K. Campbell. 2001. Evaluating microbial indicators of environmental condition in Oregon rivers. Environ. Mgt. 28(6):833-341. NHEERL-COR-2360J (S.G. Paulsen)

Traditional bacterial indicators used in public health to assess water quality and the BiologŪ system were evaluated to compare their response to biological, chemical, and physical habitat indicators of stream condition both within the state of Oregon and among ecoregion aggregates (Coast Range, Willamette Valley, Cascades, and eastern Oregon). Forty-three randomly selected Oregon river sites were sampled during the summer of 1997 and 1998. The public health indicators included heterotrophic plate counts (HPC), total coliform (TC) and Escherichia coli (EC). Statewide, HPC correlated strongly with physical habitat (elevation, riparian complexity, % canopy presence, and indices of agriculture, pavement, road, pasture, and total disturbance) and chemistry (pH, dissolved O2, specific conductance, acid-neutralizing capacity, dissolved organic carbon, total N, total P, SiO2, and SO4). FC and EC were significantly correlated generally with the river chemistry indicators. TC bacteria significantly correlated with riparian complexity, road disturbance, dissolved O2 and SiO2, and FC. Analyzing the sites by ecoregion, eastern Oregon was characterized by high HPC, FC, EC, nutrient loads, and indices of human disturbance, whereas the Cascades ecoregion had correspondingly low counts of these indicators. The Coast Range and Willamette Valley presented inconsistent indicator patterns that are more difficult to characterize. Biolog systems were not successful, nor did a statistical pattern emerge between the first five principal components and the other environmental indicators. Our research suggests that some traditional public health microbial indicators may be useful in measuring the environmental condition of lotic systems.

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