Watershed health — Mid-Columbia update

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Regional summary

• B-IBI scores in the Mid-Columbia Region show that a majority of streams are in good biological condition.
• The most prevalent stressors for streams in the Mid-Columbia Region were elevated water temperatures, higher phosphorous concentrations, higher proportion of sand/fines, human influence, and low canopy cover.

Biological condition

Invertebrate biological condition of streams, as assessed with B-IBI scores, did not change significantly from 2011 to 2015 in the Mid-Columbia Region. For both rounds of sampling, most streams had good B-IBI ratings. The proportion of streams in poor condition decreased, and those in fair condition increased. These are positive trends that will require more data to validate.

Significant physical and chemical stressors 

In the Mid-Columbia Region, warm water temperatures continue to be one of the leading physical stressors, with more than half of streams showing elevated values. Although not significant, the number of stream kilometers with eleveated phosphorus and sand or fine sediments increased between 2011 and 2015. Additionally, some of the other most common physiochemical stressors in this region were those associated with water quality, reduced canopy and fish cover, and human influence.

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

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