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Method Comparison: Analysis of Fecal Coliform Samples from Washington State Estuaries

Publication number Date Published
14-03-019May 2014
VIEW NOW Method Comparison: Analysis of Fecal Coliform Samples from Washington State Estuaries (Number of pages: 31) (Publication Size: 925KB)

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Author(s) Mathieu, N.
Description During 2012-2013, the Department of Ecology conducted an analytical comparison study of two methods used to determine fecal coliform bacteria concentrations in water samples. The purpose of the study was to determine whether a relatively new chromogenic substrate method, Colilert®-18 (CS-C18), could be used for estuarine water samples in place of the well-established multiple tube fermentation (MTF) method with an A1 growth medium (MTF-A1).

For samples with relatively low bacteria levels, results showed that the experimental CS-C18 method indicated bacteria concentrations significantly lower than the conventional MTF-A1 method.

Recommendations from this study include: (1) continue using established MTF methods in Washington State, (2) conduct future studies to investigate the cause of the method discrepancy, and (3) collect additional comparison samples at a higher concentration range.
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Keywords Colilert, MPN, estuaries, shellfish, fecal coliform
WATERSHED Water Resource Inventory Areas
(WRIA 01,WRIA 14,WRIA 18,WRIA 24)
DATA Environmental Information Management (EIM) #NMat0005


Quality Assurance Project Plan: Fecal Coliform Method Comparison Study in Estuarine Waters of Washington State