Taking the guesswork out of water pollution — reports available from projects that use DNA to track sources of fecal contamination

When fecal bacteria contaminates our waters and threatens the health of people, salmon, and shellfish, how do we make our water clean again? We can invest in potential solutions based on a best-guess about the source of pollution, or — as two new studies funded by the Washington State Conservation Commission (SCC) have indicated — data can be gathered to help trace fecal bacteria back to its source.

In 2018, the SCC awarded two $200,000 contracts for projects that would use a method called microbial source tracking (MST) to analyze DNA collected from water samples and connect fecal bacteria to its origin (e.g. human sewage, livestock, wild/domestic animals). Both projects were conducted in areas of Puget Sound, one in Pierce County and one in Whatcom County, where concentrations of fecal coliform bacteria impact shellfish harvest.

Final reports from the studies have been submitted to the SCC and are available now:

Both reports offer recommendations for the most appropriate methods to reduce fecal contamination in the project areas, such as repairing septic systems, cleaning up pet waste, and making changes to livestock management practices. The reports also include lessons-learned and suggested MST protocols for future projects.

Questions about these projects? Please contact Karla Heinitz (kheinitz@scc.wa.gov or 360-407-6212).

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Mt Baker and Puget Sound