Watershed health — Snake River update

We investigated the health of stream habitats in the Snake River Status and Trends Region in 2011 and 2016. From these two study years, the region showed a similar biological condition, with the highest stressors involving stream chemistry and human influence.

River with fallen woody debris and dispersed fir trees around it

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Regional summary

  • B-IBI scores in the Snake River Region show the proportion of stream kilometers classified as being in good biological condition slightly decreased from 2011 to 2016.
  • The most prevalent stressors for streams in the Snake River Region were high water temperatures, elevated nutrient concentrations, increased human influence, high pH, and increased substrate embeddedness.

Biological condition

Invertebrate biological condition of streams, as assessed with B-IBI scores, did not change significantly from 2011 to 2016 in the Snake River Region. The proportion of streams classified as good, fair, or poor were not significantly different. However, the percentage of poor B-IBI scores decreased, and the fair and good scores increased slightly.

Graph showing slight decrease in the proportion poor streams and slight increase in fair streams.

We used B-IBI ratings from 2011 and 2016 to obtain the percentage of stream kilometers in good, fair, and poor conditions for the Snake River Region. Error bars represent 95% confidence intervals.

Significant physical and chemical stressors 

In the Snake River Region, the most prevalent physiochemical stressors pertained to water chemistry, including increased nutrients, elevated suspended solids and high pH. Other prevalent stressors in this region were those associated with water temperature, human influence, and stream substrates, namely high embeddedness and elevated sand or fines. Many of these conditions were widespread in the region, with eight stressors being found in 60–90% of stream kilometers assessed.

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 Snake River Region for 2011 and 2016. The x-axis represents the percentage of river extent in poor condition. Error bars show 95% confidence intervals.

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