Restoration on French Creek Tributary Supports Local Salmon
/The life cycle success of a salmon depends directly on the water quality of our streams and rivers. They thrive in cold, clean, and clear water. However, in locations along French Creek, which feeds into the Snohomish River, the water is often warmer than it should be for salmon and other fish, particularly during the summer.
One of the ways our Habitat Restoration Team has been helping to change this is through a restoration project on a tributary of French Creek. The site was overgrown with Himalayan blackberry. While shade from vegetation helps cool water temperatures, not all vegetation is equally effective. Common invasive species such as Himalayan blackberry and reed canary grass don’t grow tall enough to provide the necessary shade to waterways. They also crowd out vital native shrubs and trees, preventing continuous canopy.
An area of the site filled with Himalayan Blackberry at the start of the project.
A meadow near the French Creek tributary planted with live stakes.
Removing invasives like Himalayan blackberry isn’t easy.
“Blackberry is difficult to remove both because it has a persistent root ball that will grow back when the bramble is mechanically removed or treated with herbicide, and because it is spread by birds, which allows it to reach places easily even if there isn't a local population,” explained James Lauder, Habitat Restoration Project Manager at Snohomish Conservation District.
A beaver dam on the French Creek tributary site.
Once our Habitat Restoration Team does the hard work of removing invasive species like Himalayan blackberry, native vegetation can be added. At the French Creek site, these native plantings include willow live stakes. Willows are able to grow in moist soil, making them a suitable option for streamside restoration. Their roots are useful in preventing streambank erosion, decreasing the amount of sediment in the water to support fish habitat.
Willows are also a preferred food source for beavers. The restoration work at this French Creek site has attracted some of these natural ecosystem engineers who have now created two dams and pools in the stream. This added complexity increases French Creek’s habitat value for fish and other wildlife.
The idea of a beaver dam on your property might inspire some concern, but as it turns out, there are many benefits to encouraging beavers on your property. Beaver dams form ponds that retain water, recharging groundwater supplies and reducing flooding during rainy periods. This water retention also creates more reliable stream flow during hot weather when streams may otherwise dry up due to low water inputs and high temperatures. The complex wetlands that can result from beaver activity also help with filtering pollution.
Beaver dams also create habitat for salmon. The deep pools filled with woody debris around beaver dams provide areas for fish to find food and hide from predators. The water in these pools moves much slower than the rest of the stream, creating a place where salmon can rest.
In addition to removing invasives and planting native vegetation, the District installed a fence to keep livestock on the property out of the water. This helps to protect the new plantings, prevents erosion, and helps keep manure and sediment out of the creek.
The factors that contribute to water quality can be complex, and require multiple interventions to improve overall stream health. These practices are ultimately worth it. When stream quality improves, many species benefit, including our beloved PNW salmon.
This project has been funded wholly or in part by the Washington State Department of Ecology. The contents of this document do not necessarily reflect the views and policies of the Washington State Department of Ecology, nor does the mention of trade names or commercial products constitute endorsement or recommendation for use.
