Restoration efforts to build floodplains, encourage native habitats
With the help of the Scappoose Bay Watershed Council, the confined South Scappoose Creek will soon flow with the freedom it once had.
The narrow veins of the South Scappoose Creek watershed branch into the green hills west of the city. This network of channels pulls water from the surrounding hills and funnels it into South Scappoose Creek.
Constricted by urban and agricultural development over the years, the creek no longer flows at its own will; instead, steep banks force the creek to cut deeper into the earth, causing erosion and degrading the surrounding environment.
Now, its up to the Scappoose Bay Watershed Council to come up with a plan to restore the creek.
The main problem with the creek is that its disconnected from the floodplain, said Chas McCoy, coordinator for the Scappoose Bay Watershed Council. It may seem beneficial to prevent creeks from flooding, but in reality, a creek without a floodplain will suffer from erosion. I see flood as more of a social term; people view floods as destructive, but they are a natural process, McCoy said.
The creeks banks are valuable for native species that depend on riparian habitats. As the creek continues to erode, these habitats are lost, discouraging salmon, turtles and other native inhabitants from residing in the creek. Its a vicious cycle once the key, native species abandon the creek, the ecosystem is further compromised.
The watershed council has flagged a stretch of South Scappoose Creek that runs through Veterans Park as a section of high priority, but the restoration is limited by existing or planned development, private land ownership and, perhaps, most daunting, limited funds.
Barriers to Restoration
In 2009, The Scappoose Bay Watershed council drafted a restoration plan that focuses on a five-mile stretch of South Scappoose Creek running through the city of Scappoose. The plan breaks the five miles up into 18 management areas, ranked by priority. Out of the 18 management areas, the watershed council has checked off two. The goal of the restoration effort is to ease the grade of the vertical banks to 25 percent. This creates flood zones and alleviates the force of the water flow; in turn decreasing incision, McCoy said.
Creek restoration efforts are expensive and hard to fund, McCoy said. Since there is little increase in property value when restorations are completed, funding sources tend to be hesitant due to the high cost of restoration in comparison to the resulting value bump.
Currently, the primary revenue source for the South Scappoose Creek restoration is the Oregon Watershed Enhancement Board, which allocates lottery dollars to the watershed council for such projects. The watershed council, however, will need find a lot more money in order to move forward with the 16 remaining management areas. The two completed projects together cost about $280,000, McCoy said.
We have to bring in large excavators, then we have to haul all of the dirt off site or it will defeat the purpose of the project, McCoy said. We have to pay to haul the dirt, then pay to dump it at the quarry.
When planning the floodplain construction, the watershed council has to work carefully with landowners. Im not trying to complain about development, said McCoy. We need homes, and next to the creek is nice, but the development will cause issues with restoration projects.
In the late 19th century and early 20th century, removal of marketable timber and a rapid increase in agriculture and grazing began to take a toll on the valleys soil. As a result, levees were built to control drainage of the tributary. Gradually, this process confined South Scappoose Creek to the narrow corridor we see today. According to the restoration plan, It is likely that the creek was forced into a single channel at the margins of the valley floor to maximize useable farmland, a process which likely resulted in early channel incision.
Restoration on the stretch of the creek that runs through Veterans Park will be delayed until the bridge on JP West Road is reconstructed in 2014, a project with an estimated cost of around $1 million.
The bridge is in pretty bad shape structurally, said Brian Varricchione, the city planner for Scappoose. Currently, the bridge has posts supporting it from the creek bed, disrupting flow and catching debris. The new bridge will extend all the way across the creek with no obstructions, Varricchione added.
The Scappoose Bay Watershed Council hopes to have a funding decision for the Veterans Park floodplain restoration made this year, and is aiming for a 2015 completion on the project.
The unhealthy habitat on the banks of the creek causes trees, shrubs and other types of vegetation to thin out, resulting in an all-around less shady creek with higher temperatures.
Higher water temperatures may seem inviting to residents looking to take a dip, but some of the streams inhabitants, notably temperature-sensitive salmon, will likely move away from warmer water.
The temperature limit for salmon is 18 degrees Celsius, McCoy said. And Im certain that the creek exceeds that in the summer.
Although South Scappoose Creek is one of the main salmon-bearing creeks in the watershed, salmon numbers are in a slow decline.
Trends for Scappoose in general are fairly stable in comparison to 2011 numbers, said Dave Stewart, stream restoration biologist at the North Willamette Watershed District. But compared to the 10-year average, numbers are down a bit.
In 2011, estimates for coho salmon in the creek were under 300 spawners. Generally speaking, the creek should have 500-600, Stewart said. Coho arent the only salmon relying on the creek, but they provide the most solid data, he added.
Although floodplain restoration projects benefit salmon, it takes a lot of time relate annual runs to specific restoration projects, Stewart said. These projects take a long time and fish could take five years to return to the watershed, he added.
The trends for salmon in the Scappoose watershed are reflective of most watersheds feeding the Columbia, Stewart said. Aside from salmon, there are a number of different species of high importance, including two varieties of native turtles that rely on the creek.
What were doing in Scappoose is going to benefit everything downstream, including fish in lower Columbia tributaries, Stewart said.Add a comment