It’s a Prickly Situation: Constructing a Living Fence by student Meredith Moses

Volunteers learning about the river past and present

It was a beautiful late winter day.  The sun was shining, it was cool, but not cold, a perfect day for planting.  We were planting native vegetation at the Lower Lions Reach Natural Area on the Cedar River. 

 Today we built a living fence between King County land and the neighboring privately held parcel.  This was a case of a good fence making good neighbors.  Here’s why.

Knotweed is an invasive plant originally from Asia.  Long ago, it was imported to Europe as an ornamental, and then it traveled to North America in the 1880s.  Knotweed will crowd out native plants and damage habitat, especially along riverbanks. It is also terribly destructive to property because it grows in a way that destabilizes those riverbanks, causing serious erosion problems.  However, it grows tall and looks rather like bamboo, making it effective as a screen.  This is why the neighbor wanted to keep the knotweed to act as a barrier between private and public property.  The public uses this stretch of the river frequently during the summer months.  With all the attendant noise and trash that can accompany summer river visitors this landowner wants a a divider of sorts to separate his home from the public lands. Our team had to get creative to meet this challenge! 

Knotweed: Public Enemy Number One

 Working together, people from King County, Friends of the Cedar River Watershed, the Cascade Land Conservancy and the landowner came up with a plan to satisfy everyone.  First, the county land was cleared of knotweed.  Next, they planted a living fence made of thorny native plants along the property line. The plan is that when the fence, also known as a hedgerow, is big enough, the knotweed can be removed from the private land.  Both knotweed and trespassers will be discouraged by a prickly barrier. 

So on this beautiful day we planted a modern native plant hedgerow in the traditional English style, two parallel rows of native plants.  We planted Nootka rose, Black Hawthorne, Vine Maple, Red Osier Dogwood, Salmonberry, and Tall Oregon Grape.  Most of these plants are “armed” with thorns or stickers, making the hedgerow a very real fence. 

Preparing the ground for the native plant fence

After we got our orientation, planting instructions, and safety briefing, we split up and started planting.  I picked the area nearest the river and enjoyed a river concert while I was planting.  All 300 plants were in the ground by lunchtime. 

 On our lunch break, a Cedar River Salmon Journey Naturalist came and spoke to us about the history of the Cedar River and its salmon.  Originally, the Cedar came down from the Cascades and joined the Black River, which joined the Green River, which became the Duwamish, which is actually an estuary that runs out to Elliot Bay.  At that time, the Cedar was spawning ground for the chum and pink salmon.  Both the pink and chum salmon need the Duwamish estuary to make the transition between fresh and salt-water habitats.

The Cedar River flowing through Lower Lions Reach

In the early 1900′s the Cedar was re-routed in Renton so that it ran directly into Lake Washington.  This accomplished two important goals, flood control for the City of Renton and stabilization of the water level in Lake Washington.  With the water level in Lake Washington stable, the Ballard Locks were built, which effectively killed what was once the Black River and cut off the salmon access from the Duwamish to the Cedar River.  We lost both the pink and the chum runs and for a while, there was no salmon in the Cedar. 

 In the 1930s, the City of Seattle decided to re-introduce salmon to the Cedar River.  Sockeye naturally live in rivers with lakes.  The little salmon live in the lake for a couple of years until they are big enough to move on to fresh water.  So they seeded the river with sockeye and there been salmon in the Cedar since then. 

After lunch, we placed mulch around all the plants, cleaned up and stopped for the day.  All this was accomplished by about 20 — 25 people in around 4 hours. Quite a productive day!

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