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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

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

Table of Contents
Fecal Coliform

Historic

No data are available to characterize historical conditions for this parameter in this subwatershed.

Current

As a part of their Stephens Creek and Westside Streams Water Quality Monitoring Projects, BES sampled Stephens Creek for fecal coliform from December 1996 to June 1997 and from August 2002 to March 2003. A total of 36 samples were taken at five sites throughout the Stephens subwatershed (1D, 2D, 3D, 4D, and W4). Six samples each were collected from sites 1D and 2D, while 7, 9, and 8 samples were taken from sites 3D, 4D, and W4, respectively. In 12 of the 36 samples, fecal coliform concentrations were qualified as estimated concentrations. Five of the fecal coliform concentrations are lower concentration limits. The fecal coliform concentrations observed at the sampling locations ranged from 36 to 16,000 cfu/100mL. Setting the qualified data to the reported concentrations, the average fecal coliform concentration is 1,500 cfu/100mL with a standard deviation of 2,700 cfu/100mL. Table 17) presents a summary of data and findings for the Ssubwatershed.

Assessment

No fresh water quality criteria exist for fecal coliform. Bacteria criteria for Oregon are stated in terms of E. coli concentrations. As indicated above, 68% of E. coli concentrations exceed the single sample maximum E. coli criterion indicating that E. coli is a potential water quality concern for bacteria in Stephens Creek. However, a data set that includes monthly sampling spanning a twelve month period and including two to three sampling events conducted during wet weather is minimally needed to make a determination about whether or not E. coli is a water quality concern.
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