Watershed health — Unlisted Washington update

We investigated the health of stream in the Unlisted Washington Status and Trends Region in 2010 and 2019. In these study years, we saw the region's streams mostly in poor biological condition, with the highest physical indicators involving stream substrate.


Large river surrounded by dry grassy hills.

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Regional summary

  • Benthic Index of Biotic Integrity scores for the Unlisted Region show a majority of streams to be in poor biological condition.
  • The most prevalent indicators for streams in the Unlisted Region were increased sand and fine sediments, increased nutrient concentrations, and increased substrate embeddedness.

Biological condition

Invertebrate biological condition of streams did not change meaningfully from 2010 to 2019 in the Unlisted Region. We did see a shift from fair to poor condition in 2019, as compared to 2010, but this is a small change. Most notably from these findings, it shows that both years of sampling have a majority of stream kilometers classified as being in poor biological condition.

Graph showing a majority of streams being categorized as poor using B-IBI score.

We used B-IBI ratings from 2010 and 2019 to obtain the percentage of stream kilometers in good, fair, and poor conditions for the Unlisted Region. Error bars represent 95% confidence intervals.

Significant physical and chemical indicators

In 2010 and 2019, four indicators were categorized as poor for over 50 percent of the stream extent assessed. In 2019, two of those indicators were over 80 percent, including bed stability and percent sand fines.  Nitrogen, phosphorus, and average embeddedness were also poor in a high percentage of stream extent sampled, remaining over 50 percent for both 2010 and 2019.

To interact with this graph and learn more about these physiochemical indicators, hold your mouse over each bar.

This interactive graph shows the percentage of stream kilometers assessed with poor physiochemical conditions in the Unlisted Region for 2010 and 2019. The x-axis represents the percentage of river extent in poor condition. Error bars show 95% confidence intervals.

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