Category Archives: Restoration
All over Oregon, landowners are planting native trees and shrubs to restore forests to places they once thrived. In the Willamette Valley, this work often focuses on restoring forests within the floodplains of rivers. When a water body interacts with its floodplain, whether it is for a few days or for months at a time, all sorts of amazing things happen!
Water quality can be improved significantly when water interacts with the floodplain. Water velocities will slow, allowing suspended sediments (dirt, sometimes carrying pollutants) to settle out of the water and deposit on the floodplain, resulting in less turbid (dirty) water, which is good for aquatic species and for people.
Depending on the composition of the soil in the floodplain, water can soak into the ground and replenish groundwater, or water can pond on clay deposits and create wetlands which support a diverse array of wildlife. When water soaks into groundwater, it can stay there for weeks or years, and over time will become cooler. This cooler water often seeps back into the river creating cold water zones that cold-water fish, like salmon, can use for migration, resting, feeding or spawning.
Water also picks up a lot of material when it interacts with the floodplain, ranging from small particles of leaves and insects to huge trees. Many of Oregon’s native fish and wildlife are dependent on these materials to provide food or suitable habitat to survive. Salmon, for example, will eat insects picked up by floodwaters, and they also depend on diverse habitat in the river that large log jams formed from floodplain trees can provide. Salmon are only one example of a large number of native species that depend on good water quality and complex aquatic habitat.
Even when floodwaters don’t actually reach a nearby forest, a mature native forest located near a river (a riparian forest) can still provide numerous benefits including shade to cool river water, and habitat for the large number of species who depend on riparian habitat in Oregon. These hardwood forests provide wintering habitat and movement corridors for songbirds, mammals, amphibians and reptiles. Breeding and migratory bird densities in cottonwood-dominated riparian forests are generally the highest of all habitat types in North America.
Oregon State Parks has partnered with numerous organizations and individuals to restore floodplain forests at sites along the Willamette River. The Willamette is one of many rivers that have been largely disconnected from its floodplain over time as other land uses have come to dominate the landscape. In the 1850s it is estimated that hardwood riparian/floodplain forests occupied 67% of the riparian zone along the Willamette River main-stem, reduced to less than 10% by 1990. Many of OPRD’s Willamette River Greenways and some of our state parks and natural areas contain areas that used to be dominated by forest, where land conversion has occurred over time.
To properly start a forest from scratch, you need to keep in mind a number of principles borrowed from the fields of forestry, botany, and agriculture. The density, arrangement and species composition that you plant in year 1 will influence how your forest appears and functions in 10, 50, and 100 years from now, at maturity.
Different species have vastly different tolerances to environmental conditions, such as flooding, animal damage (deer, voles, beaver, etc.), competition with other plants, drought, and other factors. These differences will influence which species survive over time and are present in your future mature forest. How you prepare your site prior to planting, and how you manage your planting area for the first 5-10 years will also greatly influence your future mature forest.
Restoration practitioners in the Willamette Valley have implemented a number of different approaches to floodplain and riparian forest restoration, with none of them being inherently “right” or “wrong”. Instead, your chosen approach will depend on your desired future condition (i.e. what you want your site to look or function like at some time in the future), what your starting site conditions are, what foreseeable problems may come up at a site, planned management interventions at the site , and of course, what financial and staff resources you have available.
Notable examples of floodplain and riparian forest restoration work occurring at Oregon State Parks sites within the Willamette Valley include Luckiamute Landing State Natural Area, Half Moon Bend Landing, Darrow Rock’s Landing, Elijah Bristow State Park, and Willamette Mission State Park. These projects are using a variety of approaches in their density, arrangement, and species composition based on site specific conditions. Over time, all of these project areas will mature and begin to provide the ecological functions of improved water quality, shade, habitat complexity, and food sources for native fish and wildlife.
Cape Lookout State Park on the north Oregon coast is home to dramatic scenery and diverse wildlife habitats, containing everything from basaltic ocean cliffs, sand dunes, and majestic Sitka spruce forests. The park has an enviable location with facilities situated between the remarkable cape which juts 2 miles out into the Pacific Ocean and Netarts Bay, the latter of which is arguably one of the more pristine bays on the Oregon coast.
This summer, Cape Lookout has also been the host of a large stream restoration project designed to improve the park’s aquatic resources. Jackson Creek is an ocean tributary contained mostly within the park’s boundaries that flows through the picnic area before running out to the ocean on the cobble and sandy beaches just north of the headland. The Jackson Creek watershed encompasses just 1.6 square miles but provides excellent habitat for coho, sea run cut throat trout, winter steelhead, and many different species of amphibians. The upper part of the watershed is steep and Jackson Creek forms a deep, narrow canyon east of the Park. As the stream enters the Park, it enters the flat coastal plain, where the channel becomes less steep. It is here, within the boundaries of Cape Lookout State Park, the creek provides important spawning and rearing habitat for fish.
Jackson Creek has an interesting history and has long been impacted by a series of human caused disturbances that have resulted in its habitat being compromised. In 1950, the creek was diverted into an excavated channel and directed into Netarts Bay. According to an article in the April 9, 1950 issue of the Oregonian, this action was undertaken by Tillamook County with the hopes of improving the salmon fishery. It was also hoped by some that the increased fresh water into Netarts Bay would help clear out sedimentation and improve commercial oyster production.
These intentions were well meaning, but ended up having negative impacts on aquatic habitat. It turns out that Netarts Bay is naturally a very saline environment, with only 14 small perennial streams providing a source of fresh water to the bay. In fact, the bay flushes itself with only 1.6 tidal cycles which is pretty rapid for a bay of its size. The fresh water contribution from diverting Jackson into the bay was minimal. Also, the creek likely contributes more to sedimentation, particularly in the south side of the bay where it regularly delivers material from the steep slopes of the Tillamook Highlands.
Diverting the creek into the bay also effectively cut off the ocean tributary from fish use. But this didn’t last long. A few years after the creek was diverted, it broke through the construction dam and some flows returned to the original channel. The flow of the creek has then been split between both channels- the historic ocean tributary and the newly constructed diversion channel- for the past 60 years. This had dramatic effects on the aquatic habitat. While fish have been using both channels, neither channel has had enough water in it to effectively support high quality fish habitat. Additionally, the diversion channel frequently went dry in the summer months and would strand juvenile salmon in small pools that eventually went completely dry. The diversion channel was also very unstable. It transported large amounts of coarse gravel downstream, and then would jump its banks and flow into portions of the campground. It wasn’t uncommon during these events to see juvenile salmon stranded in puddles in the campground!
Clearly, something had to be done. This summer, the Oregon Parks and Recreation Department teamed up with partners the U.S. Fish and Wildlife Service, Tillamook Estuaries Partnership, the Oregon Department of Fish and Wildlife, and the Oregon Watershed Enhancement Board to implement a large stream restoration project on Jackson Creek. As part of the project, the diversion channel was plugged and historic flows returned to the original Jackson Creek channel. A road ford, which had park vehicles driving across the creek to access the water treatment plant, was removed and a timber bridge will be installed to provide safe fish passage for all life cycles of salmon. And finally, the water intake that provides water from Jackson Creek to the park for use was effectively screened to prevent fish from becoming trapped in the park’s water system.
With all these improvements, it is hoped that adult fish will have an easier time navigating the ocean tributary as they come in from the ocean to spawn. Natural resources staff also hope that the original Jackson Creek ocean tributary will become more connected to its floodplain with the increased flow, providing a better place for young coho to rear. All in all, the creek has been returned to its natural condition and will provide a better experience for all park visitors- both human and fish!