Photo: Jay Mather.

Looking at the Whychus Creek Restoration: Four Years Later

Aug 05, 2020 by Jana Hemphill
Four years after the restoration of Whychus Creek at Whychus Canyon Preserve, how is the restoration looking and what is the data showing?

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Back in 2016, the Land Trust, working alongside multiple partners, completed the first phase of restoration on Whychus Creek at Whychus Canyon Preserve. With the goal of improving habitat in and around the creek for fish and wildlife, approximately 1.5 miles of the creek was restored in this phase of work. After four years, how is the restoration looking and what is the data showing? What are some of the indicators we can use to know how successful a restoration project has been? Let’s take a look!

Lush vegetation begins to replace drier ponderosa pines. Photo: Jay Mather.
Lush vegetation begins to replace drier ponderosa pines. Photo: Jay Mather.
Groundwater Depth. Before this restoration, Whychus Creek ran straight and was disconnected from the surrounding valley floor. Since the creek was not connected, the meadow grasses and flowers would dry up and turn brown in late summer. There was no surface or groundwater from Whychus Creek getting to these meadows like it had historically done. Groundwater depth—the distance to groundwater from the surface of the valley floor—helps us see how connected Whychus Creek is to the rest of the valley floor. The closer to the surface, the more interconnected.

Groundwater depth has been calculated by averaging the depth across a number of groundwater monitoring wells within the restoration project. Back in 2015, the average depth was 6.1 feet. In 2018 and 2019, the average depth was 1.4 feet. That’s quite a difference! We can also visually see this change since the valley floor stays green and lush throughout the summer.

Total Channel Length. For the most part, prior to restoration Whychus Creek used to be one channel. Post-restoration, we hoped that the creek would become more diverse, with multiple channels of various sizes crisscrossing, meeting back up, and running across the valley floor. What does this do? Multiple, diverse channels retain more nutrients in the water and on the valley floor following a flood, increase habitat for fish, and expand the amount of vegetation along stream banks (which in turn provides more food and shelter for songbirds, deer, elk, and other land mammals). Basically, multiple channels that are able to access the valley floor create the conditions that are necessary to bolster the foundation of the aquatic food web.

A view of multiple channels of Whychus Creek. Photo: Jay Mather.
A view of multiple channels of Whychus Creek. Photo: Jay Mather.
Before the restoration project, the total amount of stream channels (main channel and side channels) in this part of Whychus Creek was 1.1 miles. Just one year after restoration work was completed, this number grew to 3.7 miles. In 2019, it was more than four times the length before the restoration, coming in at 4.6 miles! That’s quite the increase in nutrients, habitats, and green vegetation! 

Complex Habitat. There is a wide variety of habitats that different aquatic creatures need in our creeks and rivers. With this restoration project, we wanted to increase the number of types of habitats available, from still pools to gushing rapids to riffles (a rocky or shallow part of a stream with rough water). In essence, an appropriate condition for Whychus Creek at the restoration area would be a mix of slow water and fast water habitats. This increases the number of different types of aquatic creatures that can call Whychus Creek home.

When we look at having more complex habitat, we look at the number of habitats in this stretch of the restoration project. After three years, we’re excited to say the number of habitats has increased by more than six times the number of habitats prior to restoration.  

Woody Debris. What do downed trees in Whychus Creek do? It turns out, a whole lot! Wood in streams provides hiding places for fish and other critters. Downed wood collects things like leaves, tree needles, and other organic material, helping to retain nutrients in the stream. It also helps slow the flow of water. You can learn more about the benefits of woody debris in our blog post on the topic.

Data is collected next to some woody debris in the restoration area. Photo: Land Trust.
Data is collected next to some woody debris in the restoration area. Photo: Land Trust.
During the restoration, large woody debris was added to the creek. Some of it has been pushed downstream during large flow events and some is no longer in the creek as the creek morphs and alters its path across the valley floor. Since pre-restoration, there has been a 9-fold increase in the number of pieces of wood per every 100 meters.

Creekside & Wetland Vegetation. This data goes hand-in-hand with the information collected about groundwater depth. The types of shrubs, grasses, and flowers that grow next to creeks and in wetlands is different than the types that grow in drier areas. By looking at what kinds of plants and how many there are, we can see that the acres of creekside and wetland vegetation has grown from 23.47 acres before the restoration to 28.32 acres in 2019. In addition, there are 2.4 times more creekside and wetland plant species. This is beneficial to all sorts of wildlife, including deer, elk, beaver, butterflies, bees, and grasshoppers. This is another type of data that shows that the valley floor is more connected with Whychus Creek than it was before the restoration project.

Macroinvertebrates. 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. Macroinvertebrates like the larvae of mayflies, stoneflies, and caddisflies have also shown an increase since the restoration was completed. Not only are they food for fish and birds, they are sometimes used to indicate water quality.

With this data, we can look at restoration methods and tools that worked and didn’t work in order to help inform our future restoration projects on Whychus Creek.

Thank you to the Upper Deschutes Watershed Council and to the Land Trust’s Jason Grant for helping with this blog post!

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