One of the Land Trust's partners in creek restoration, the Upper Deschutes Watershed Council, recently released their 2022 Macroinvertebrate Monitoring in Whychus Creek Report. And while the report takes a look at nine monitoring sites along the length of the creek, we were interested in diving deeper into the results from Land Trust restoration projects at Camp Polk Meadow Preserve, Whychus Canyon Preserve, and Rimrock Ranch. So let's jump in!
First, a clarification. This is a macroinvertebrate monitoring report, but what is a macroinvertebrate? Macroinvertebrates are animals that lack a backbone, are large enough to see without the use of a microscope, and spend at least some of their lives in and around water.
Overall, the report noted that the changes in the macroinvertebrate community over time suggest ecological uplift—positive trends on a series of metrics. Some of these metrics include:
A significant increase in macroinvertebrates that need low suspended sediment levels and cool water. This increase was found in both the restored portion of Whychus Canyon Preserve and Camp Polk Meadow Preserve. Lower suspended sediment levels along with cooler water are both indicators of a healthier creek. This means the creek is able to slow down and drop sediment as it flows (not keep it mixed up in the water column; learn more below), and that water temperatures are cooler due to factors like stored groundwater reserves in the surrounding floodplain and streamside vegetation. Stored, cool groundwater is super helpful during our hot summers when it is released back into the creek, bringing overall temperatures down. Learn more about groundwater.
An increase in mayflies, stone flies, and caddisflies at Camp Polk Meadow Preserve. These three types of macroinvertebrates are known to be environmentally-sensitive creatures, so if they are found in a creek, it means the habitat is looking pretty good! Learn more about why macroinvertebrates are good indicators of water quality.
A small increase in both macroinvertebrates that prefer and thrive in slighter cooler environments as well as those that thrive in slightly warmer environments in the restored section of Whychus Canyon Preserve. Having a larger variety of macroinvertebrates is a sign of a healthy creek. In this case, it shows that there are areas where water is cool (perhaps in deep pools or shaded areas) and areas where water is warmer (perhaps in areas where the Creek spreads out across the valley floor and is shallower).
A wider range of sediment in the restored portion of Rimrock Ranch, including fine sediment. Before these sections of Whychus Creek were restored, the stream flowed very fast and moved lots of fine sediment downstream. Now, in the restored section of Rimrock Ranch (for example), the creek can spread out and slow down. This causes less fine sediment to move downstream; instead it is deposited in slow moving areas or along streambanks. This is very important for building the floodplain and adding nutrients for vegetation, producing more aquatic plants, and providing organic material that microorganisms (both plants and animals) use to absorb carbon.
Learn more: