The City of Salem has been collecting monthly water quality samples in the Willamette River near the site of the swimming event since the mid-1990s. Based on an analysis of data collected between 2001 and 2016, the Willamette River scores 90 out of 100 (Excellent) year-round and 91 out of 100 (Excellent) for the month of October. These values are determined using a methodology developed by the Oregon Department of Environmental Quality. Known as the Oregon Water Quality Index, the scores provide a summary measure of the overall health of a water body based on temperature, dissolved oxygen, pH, bacteria, and other contaminants.
Additionally, to ensure safety for swimmers, the City of Salem will increase its sampling frequency during the three months preceding the triathlon, collecting seven samples between June 30 and September 29.
If any sampling results call into question the quality of the river, the swimming stage will be canceled and the race organizers will transition the triathlon into a duathlon.