Research & Science Note 8: Enviro-coli test

Development of a method for differentiating fecal E. coli versus naturally occurring (environmental) E. coli in surface water


The MRWCC initiated a fecal source tracking project in cooperation with Alberta Agriculture and Rural Development (2012) to characterize sources of fecal E. coli bacteria within the Milk River.

Using microbial source tracking methods (see: Research and Science Note7) it was determined that approximately 34% of the E. coli in the Milk River was attributed to cattle and cliff swallows. This suggests that multiple host sources contribute to fecal contamination in the Milk River.

Interestingly, approximately 50% of the E. coli did not have matching DNA fingerprints to any of the twenty different host sources that were tested. It is likely that a portion of these E. coli are from a population of ‘naturalized’ E. coli that has adapted to the water environment, and can survive longterm and possibly even grow within the turbid conditions of the Milk River.

Naturalized E. coli have been known to exist for over a decade. The key concern with these E. coli is that they are not an accurate indicator of recent fecal contamination. Their presence in a watershed can lead to the overestimation of fecal contamination, which can in turn impact recreational use. In the Milk River, as temperatures increase and flows reduce in late summer, these naturalized E. coli may become more abundant.

Current water quality tests do not differentiate between E.coli from human and animal feces and those that have become naturalized in surface water. It is therefore difficult to determine whether E. coli levels are high due to actual fecal contamination or whether they may have been overestimated due to the presence of naturalize E. coli. This project will lead to development of a method that will allow us to distinguish between fecal E. coli and naturalized E. coli. This method has been designated as the ‘Enviro-coli’ test.

Categories: Research and Science Notes
Tags: monitoring, water quality
Author: C. Jokinen ARD, L. Tymensen ARD, M. Lupwayi (MRWCC), T. Romanow (MRWCC)