Stride: Planting riparian zones helps the Tualatin River
The Tualatin River is a very important waterway in Washington County. Its importance is derived from the fact that it delivers drinking water to some 30,000 people, provides recreational opportunities for sportsmen and serves as a wildlife habitat.
There are 34 named tributaries that empty into the Tualatin River. The Tualatin River is only as healthy as the sum of the tributaries that empty into it. This is why the Tualatin Soil and Water Conservation District and Clean Water Services, are, with owners' permission, planting riparian zones along many of these tributaries.
The riparian zone consists of trees and plants that range from the shoreline to 50 to 75 feet back from the shoreline of a tributary. Where there has been farming, there is often long stretches of shoreline with no riparian zone at all. The primary reason for planting a riparian zone is to shade the water in the tributary and thus keep it as cool as it can possibly be. Cooler water has a higher oxygen content, supports better fisheries, and is generally cleaner and has less bacteria.
The riparian zone is, in itself, a habitat. A food chain lives there. Small reptiles and mammals feed on insects and plants, which in turn are food for larger animals. It also serves as cover for the elusive deer and elk population.
The planting of a riparian zone involves the eradication of two non-native species of plant: canary grass and blackberries. First, they are cut and sprayed once or twice a year for two years. The trees that are planted in the riparian zone eventually shade out the canary grass and blackberries, and these two species disappear from the landscape. It is important to rid the riparian zones of these species, because they tend to take over and they don't make for good cover.
I have hiked along the Jackson Bottom Wetlands Preserve section of the Tualatin River just south of Hillsboro. There it has a significant amount of silt and algae and it is slow-moving. Upstream from the community of Cherry Grove is the upper Tualatin River, better known as the Lee Falls area. Originating in an old growth forest with lots of shade, the water is cold, clear and running fast. The upper Tualatin is a very healthy river, much healthier than the lower stretches.
When the river hits the plains where the farmland is, this is where most of the riparian zones need to be planted. Clean Water Services and the Tualatin Soil and Water Conservation District are paying landowners for letting them plant riparian zones on their land. This is an extra incentive for landowners. All the landowner has to do is sign the papers, watch the crew do their work and collect the money. The mature riparian zone will be a park-like setting free of berries and canary grass. It will be a great gift to future generations.
The creation of riparian zones along the Tualatin River and its tributaries will allow it to run cold, clean and clear like it did before farming and development came to the Tualatin Valley.
Washington County should be commended for its efforts to keep the Tualatin River healthy.
William Stride is a published author and outdoor enthusiast. He lives in North Plains.
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