New DRA Poster

In March 2020 the DRA attended the Oregon chapter of the American Fisheries Society Annual Meeting in Bend, Oregon. We presented a poster with the results of our benthic sampling study in the lower Deschutes River and the implications for fish. Our poster was well received. The feedback from attendees was that the Deschutes River Alliance’s monitoring efforts are important and should continue.

Photo Caption: Non-insect abundance and their contributions to salmonid parasites in the Deschuts River, OR poster. Benthic sampling data was collected and analyzed by the DRA and our poster was presented at the Oregon chapter of the American Fisheries Society Annual Meeting on March 4, 2020. (Find the poster here)

            The results of our analysis showed an alarmingly high abundance of polychaete worms and snails and included the following key findings:

• Polychaete worms host a parasite called Ceratonova shasta that is often lethal for fish. Declines in returning adult Chinook salmon in the Klamath River are attributed to the C. shasta parasite.
• Snails host a worm-like fluke parasite that causes black spot disease in fish. 
• Samples represented overall “poor” stream condition.
• Non-insects accounted for >50% of the total abundance in all samples.

We believe the simplest explanation for these results are the declines in water quality that we’ve seen in the lower Deschutes River as a result of Selective Water Withdrawal Tower passing warm, nutrient rich surface waters from Lake Billy Chinook into the lower Deschutes River. These findings highlight the urgency for immediate improvements in water quality. Increased nutrient loads combined with warmer water temperature in the winter through early summer has led to nuisance levels of algae and aquatic plant growth since surface water withdrawal began at the Tower in Lake Billy Chinook. 

            Cooler water temperatures will help ameliorate the effects of these parasites. Improvements to water quality (i.e., reductions in nutrient concentrations and meeting Oregon’s water quality standards) can restore the robust and healthy insect communities of mayflies, caddisflies, and stoneflies. Oregon’s water quality standards were set to protect the beneficial uses of streams including supporting aquatic life. We will continue to advocate for the managers of the Tower to reduce water temperature and meet state water quality standards to the maximum extent possible as the most immediate solution to restore the lower Deschutes River. Read DRA’s recently published position statement on all the issues here (link).