Water Quality

Water Quality Analysis
The Water Quality Comparison Table lists the quality of Wilsonville's treated water in relation to drinking water standards established by the U.S. Environmental Protection Agency. The latest Water Quality Report is available online.

Willamette River Water Quality Study
The Tualatin Valley Water District (TVWD), which, along with the City of Wilsonville, is part owner of the Willamette River Water Treatment Plant, recently contracted with an independent laboratory team to collect and analyze samples from the Willamette River Water Treatment Plant. This team not only tested the finished (treated) water, but also the raw (untreated) water, as well as the sediments at the bottom of the river.

The team’s findings were presented to the TVWD Board at its November 19, 2003 meeting in the form of a 235-page report, as well as testimony from team members. The results of the team’s study showed that all samples (finished water, raw water, and sediments) are exceptionally clean.

Key Findings
Wilsonville’s former Public Works Director, Jeff Bauman, had the opportunity to review the report and provide comments at the TVWD Board meeting. Bauman’s remarks included the following:

The Tualatin Valley Water District should be commended for this thorough and independent analysis. It represents a massive amount of data on not only the finished water from the Willamette River Water Treatment Plant, but also the raw (untreated) river water as well as sediments from the bottom of the river. Three brief observations from the study should be made:
  1. The results of this testing are completely consistent with the sampling conducted on the same day by the operators at the Willamette Water Treatment Plant. The results are also consistent with the 30 prior rounds of sampling - including the 1998 data set that was scrutinized in detail by TVWD's quality assurance consultant earlier this year.
  2. Inorganic compounds such as metals are naturally occurring and were either below the detection limits or were found at extremely low, background levels. Of even more interest are the more than 140 organic compounds that were tested. These were not randomly selected chemicals. They are the ones of greatest potential concern to public health. They include all the organic compounds regulated by drinking water standards; the organic compounds under consideration by EPA for future regulation; and agricultural pesticides used throughout the Willamette basin.
    • Finished Water Quality
      The treated water is far better than required by drinking water standards. In fact, all of the organic chemicals were below the laboratory detection limit, with the exception of trace amounts of byproducts from the disinfection process, which one would expect to see in properly disinfected water. (Note: The Bull Run water supply has higher levels of these byproducts than the Willamette water supply.)
    • Raw Water Quality
      All of the 140 or more organic chemicals were below the laboratory detection limit in the untreated river water. The results of this raw water monitoring demonstrate that even before water enters the treatment plant, the Willamette River at Wilsonville is clean enough to easily meet drinking water standards for all these organic chemicals.
    • River Sediment Quality
      All of the 140 or more organic chemicals were below the laboratory detection limit, with the exception of DDT (which is no longer in use). The level of DDT found was only a trace amount, barely above the laboratory detection limit. Another chemical of interest is dioxin. As a member of the laboratory team mentioned, the dioxin of concern for drinking water was not detected, even in the sediments. A far less harmful species of dioxin was detected in the sediments, but at such a low level that from a toxicity standpoint it is nearly equivalent to the pure water in the laboratory sample blank.
  3. From a public policy standpoint, it is up to each city and water district to decide for themselves whether or not they wish to utilize the Willamette River as a source for municipal water supply. Nonetheless, from a technical and public health standpoint, the data presented to you this evening verify what the City of Wilsonville has shown all along - namely, the Willamette River is a viable and safe alternative.