Watershed health — Unlisted Washington update

We investigated the health of stream habitats 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 stressors involving stream substrate.

Large river surrounded by dry grassy hills.

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Regional summary

  • B-IBI scores for the Unlisted Region show a majority of streams to be in poor biological condition.
  • The most prevalent stressors 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, as assessed with B-IBI scores, did not change significantly 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 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 stressors

Some of the most widespread physical stressors in the Unlisted Region were those associated with the stream substrate, including sand/fines, embeddedness, and low bed stability. Some chemical stressors, such as elevated phosphorus, nitrogen, and suspended solids were also prevalent in the Unlisted Region.

To interact with this graph and learn more about these physiochemical stressors, 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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