The principal strategy for coho recovery, and for their ultimate "de-listing" from the Endangered Species Act will be the restoration of degraded freshwater habitat. Though there are some regulatory provisions aimed to prevent further damage to coho habitat, this will be accomplished primarily by working with cooperating private landowners. The Elk Creek Watershed Council has been working with private landowners in the watershed to develop habitat restoration projects for more than ten years.
There are many factors that have contributed to the salmon’s decline, but one of the biggest is the loss of high quality spawning and rearing habitat. Over the years, as the land in the Elk Creek watershed was settled and developed, land management actions that improved the economic benefits of the land have taken a toll on the quality of the habitat that the salmon rely upon for their survival.
Actions such as straightening stream channels to increase pasture land, removing logs and other debris to reduce flooding, draining wetlands for agriculture, and ditching the roads along the creeks to improve drainage, all have contributed to changes in how our streams function. Perhaps the most damage was done by “stream cleaning,” a required forest practice in the 1960s and 70s, which removed nearly all the large wood from the streams in the belief that this would help the salmon that were returning from the ocean to spawn.
All these actions have increased both peak flows and water velocities. This means that more water is transported into the stream channels, it gets there faster, and it also has more energy. More water in the streams, with more energy, means more erosion. Some of this erosion is reflected in collapsing streambanks, but in our watershed, this has led to serious streambed erosion. Many of the streams in the Elk Creek watershed have eroded all the way down to bedrock. These channels are efficient in getting water out of the system quickly, and in reducing flooding, but they provide extremely poor habitat for young salmon.
Instream Habitat Improvements
We’ve now come to realize that slowing the water in the stream channel plays a critical role in creating and preserving high-quality salmon habitat. Slowing water allows gravel to collect for spawning, and it helps to create the deep pools that support healthy juvenile salmon, especially in the summer. Deeply incised, bedrock channels have very little gravel, gravel which supports not only adult spawning, but also the invertebrates that juvenile fish need for food.
Bedrock streams with little or no gravel, especially those that are exposed to direct sunlight, quickly heat up during the summer. Many streams in our watershed become too warm to support fish in the summer, others dry up entirely.
These same streams cause problems for young coho during the winter when they need to find areas with slow-moving water to avoid being completely washed away during winter storms. One of these areas is in the floodplains, the areas adjacent to the stream where rising water overflows the banks. Deep, incised channels are cut off from the floodplains so there is little escape for juveniles. It is estimated that as few as 10% of the juveniles that survive the summer make it through the winter to begin their migration to the ocean.
The Elk Creek Watershed Council has worked closely with ODFW to design and implement many instream habitat improvement projects. Most of these projects have constructed structures of logs or boulders, and are designed to slow water, capture gravel, and create pool habitat for juvenile fish. They also provide cover for fish to escape predators.
Fish Passage Improvements
Many of the culverts that were installed to gain access to forest and farm land were sized to carry away water as quickly and economically as possible. Many of these under-sized culverts have effectively blocked access to many miles of coho spawning areas. In addition, increased water velocities through some is too great for adult salmon to swim through; and in others, the force of water through the culvert has scoured out the streambed below the culvert, leaving them perched above the level of the stream to where fish cannot jump into them to pass through.
The Umpqua Basin Fish Access Team (UBFAT) estimates there are more than 800 culverts in the Umpqua Basin that are blocking fish passage to some degree. Replacing these barriers can be one of the most cost-effective restoration actions. In some cases many miles of suitable habitat can be made available by removing or replacing a single culvert. The Elk Creek Watershed Council has replaced many of these barrier culverts with larger, “fish-friendly” culverts, or with bridges.
Healthy riparian areas (those areas along the stream banks) are important to both the water and the fish. As runoff from the uplands moves through the riparian area it is slowed and filtered. Slowing the runoff before it reaches the stream helps reduce peak flows and the erosion that goes with it. [See section on Altered Hydrology.] The buffer provided by the riparian area can also filter out fine sediment, which can impact developing salmon eggs, and nutrients (manure), which can affect water quality. The trees in the riparian area will eventually provide the large wood that is necessary to maintain a functioning stream system, and which creates habitat for the salmon.
The riparian area is also important to the fish. The shade provided by the trees and shrubs along the banks helps keep summer water temperatures down, especially in streams that are already eroded down to bedrock; and the insects that fall into the water are a vital food source for young fish. During winter storms, the floodplains in the riparian area provide slow water, and a place where juvenile fish can escape the high flows in the main channel.
Improving riparian areas is an important part of the work of the watershed council. Many of our streams are overrun with blackberries and other invasive plants. Removing the blackberries and planting native trees and shrubs can help stabilize eroding streambanks and reduce erosion. Installing fencing to exclude livestock can reduce browsing and allow the newly planted trees to grow. It can also benefit livestock managers by improving opportunities for rotational grazing.
Land management actions in the uplands also has an effect on streams. Healthy upland areas, with healthy vegetation, retain and slow water moving into the creeks; and they resist erosion and filter sediment. The Elk Creek Watershed Council has worked with local landowners, and the Douglas Soil and Water Conservation District, to improve conditions in the uplands by installing livestock crossings, alternative livestock watering systems, and erosion control projects.
The Importance of Beavers
The importance of beavers to salmon restoration cannot be over-stated. Beaver dams slow water in the streams, allowing gravel to collect, and so help to cool the water in the summer. The water held in the sediment behind the beaver dam is then released more slowly over the summer, extending summer flows. Both high summer water temperatures, and low summer flows, are major limiting factors in the Elk Creek Watershed.
Studies have also shown that beaver ponds are, by far, some of the best habitat for juvenile coho. Beaver ponds provide both cool water and an ample supply of food in the summer, and they offer shelter during winter storms. While beavers might contribute to slightly more flooding, and they can cause damage to trees along the creek, the Elk Creek Watershed Council has worked with local landowners to find solutions to these problems, and to preserve the enormous benefits that beavers provide to improving salmon survival.