Bioassessment provides new and powerful tools for river monitoring

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Stonefly nymph underwater
In addition to monthly water quality testing, SYRCL’s River Monitoring Program consists of two types of bioassesment – methods of using living creatures to tell us about the quality of our water and the health of our watershed.  Volunteers have collected benthic macroinvertebrates (BMIs) at numerous sites on the Yuba watershed since 2004.  Consisting mostly of diverse aquatic insects, the make-up of the BMI community can powerfully indicate impacts.  For example, the total number of unique taxa or “richness” numbers more than 40 at many sites in the Yuba Watershed, but as low as 24 immediately below Spaulding Dam and within tributaries impaired by mining waste. Additional insights about water quality can be gained by investigating the composition of particularly sensitive taxa such as members of these families:  Plecoptera (stoneflies), Ephemeroptera (Mayflies), and Trichoptera (Caddis Flies).

Stream bugs are neat!  But what about algae?

A bloom of filamentous algae in the South Yuba River

Algae is the source of primary production in the stream and can be very sensitive to changes in available nutrients, pollution or alteration of hydrology by dams and diversions.  There are hundreds of types of algae in our watershed. Algae is on virtually every surface in a stream, although we may only notice it when blooming. In response to concern by citizens about such blooms, SYRCL launched an algae assessment program in 2008.  Just this year, the State Water Resources Control Board published a robust procedure for collecting and analyzing algal specimens.  The authors of that procedure came to Nevada City to train monitoring last month, and we developed a monitoring plan to provide continuity with our past two years of data. The sites of interest include those below dams and in the South Yuba headwaters, as well as reference site in the North Yuba River.

River Monitors have provided excellent service to these bioassessment projects, yet we invite additional volunteers to help in the field this August and September. If you would like to help with our River Monitoring Program or learn more about bugs, algae, and water quality please contact SYRCL’s River Monitoring Coordinator, Brooke Berger, at or call 530-265-5961 ext 211.

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