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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

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Table of Contents
Bacteria
The descriptions below provide general information for each topic. Click on each topic to get subwatershed specific descriptions.

E. coli
E. coli is a specific subgroup of bacteria belonging to the fecal coliform collection of bacteria. They are found specifically in the feces of warm-blooded animals, including humans. Pet waste can be a primary source of E. coli in urban areas. In addition, waste from waterfowl congregating in urban ponds and detention basins can be a source of bacteria. E. coli can enter a river system from combined sewer overflows, illicit connections, and in stormwater. Though most strains of E. coli are not harmful to human health, high E. coli counts in river system are a good indication that there has been a sewage release recently in the area.

The current water quality criteria for E. coli, which are also indicated in (Table 3), are:
-30-day log mean criteria based on a minimum of five samples: 126 cfu/100mL
-Maximum for single samples criteria: 406 cfu/100mL


Fecal Coliform
Fecal coliform are a collection of bacteria found in the feces of both warm and cold-blooded animals, including humans. Pet waste can be a source of fecal coliform in urban areas, and waste from waterfowl congregating in ponds and detention basins can be a source of bacteria. Fecal coliform can enter a river system from combined sewer overflows, illicit connections, and stormwater. Though most strains of fecal coliform are not harmful to human health, high fecal coliform counts in river systems may indicate that there has been a recent sewage release in the area.

No fresh water aquatic life or human health criteria exist for fecal coliform. Bacteria concentrations are based on E. coli.

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