2021-2022 Whychus Watershed & Floodplain Monitoring

From 2021 to 2022 UDWC collected two additional consecutive years of continuous stream temperature and macroinvertebrate community data from monitoring stations along Whychus Creek. Data provide information about how stream temperature and macroinvertebrate community status and trends changed alongside stream flow and habitat restoration actions, summarized in two technical reports for each parameter. Temperature data show the range and median of July stream temperatures from 2010-2023 are lower than in the first decade of stream flow restoration from 2000-2009, but still consistently exceed the 18°C state standard for rearing and migrating trout and salmon and the 20°C Deschutes Basin Habitat Conservation Plan (HCP) temperature requirement in July at the warmest site on Whychus (River Mile 6; RM 6). Stream temperatures at the HCP measurement location at RM 6 exceed 24°C in most years, demonstrating the magnitude of the reductions in temperature that will need to be achieved to meet 20°C at this location for all but a week by the year 2031, year 9 of HCP implementation, as required under the NMFS incidental take permit. Macroinvertebrate data describe communities that are more diverse and more balanced in recent years compared to baseline data. Twenty-three macroinvertebrate metrics showed statistically significant trends indicating stream habitat conditions along Whychus Creek have improved since sampling began in 2005. These trends include: significantly more total, EPT, sensitive and sediment-sensitive taxa indicating cool, clear water (2-4 reaches); a significantly higher percent of cool/cold-associated taxa indicating cooler temperatures or more cool/cold-water habitat including at UDWCs flagship Stage 0 restoration project implemented in 2016 at Whychus Canyon Preserve (3 reaches); a significant increase in taxa with longer generation times, suggesting increased habitat stability, including in reaches where Stage 0 habitat restoration projects have been implemented (3-4 reaches); a higher percent of taxa associated with moving water suggesting more habitat characterized by these types of flows (1 reach); and locomotion habit of taxa suggesting more aquatic plants representing higher biodiversity, habitat diversity, and potentially primary production (6 reaches).

This project will monitor continuous temperature and macroinvertebrate communities in Whychus Creek over two years. This monitoring is a key component of a long-term comprehensive watershed-scale effort to restore the
stream habitat, flows, fish passage, and water quality necessary to support strong populations of reintroduced salmon and steelhead, native resident redband, and bull trout. Monitoring results will continue to provide insight into the status of stream conditions for salmon and steelhead spawning, rearing and migration as well as for the macroinvertebrates that are the basis of their food web. Results will also inform strategic planning, effectiveness evaluations, and adaptive management of stream flow and habitat restoration and monitoring activities.