Seattle’s new seawall – Dailyuw

Seattle is well-known for its efforts to be sustainable and environmentally conscious, and downtowns new seawall follows this trend. The new seawall, influenced by studies published by UW researchers, takes special measures to accommodate marine life.

The seawall itself is located beneath the waterfront, so while it may go unnoticed to those who walk above it, it transforms an otherwise uninhabitable concrete slab into something much closer to the original ecosystem.

The seawall was initially constructed in the 1930s. After the 2001 Nisqually earthquake, a section of the original Alaskan Way seawall began to settle. Since the structure was compromised, it became necessary to replace the wall, but in addition to the structural changes that were necessary, the new design takes into account the fact that Elliott Bay is part of the natural migration route for salmon.

Previously, the seawall was simply made of concrete, which served its purpose of protecting the citys infrastructure, but neglected to serve the original ecosystem.

Water near the shoreline is usually shallow and well lit. Both of these qualities are important for fish, especially juvenile salmon; the bright and shallow waters provide a good habitat for prey and good protection from predators. This is crucial for young salmon in Elliott Bay since the fish use the waterfront to migrate and to acclimate to salt water, growing considerably in this time.

The old concrete seawall disrupted the natural salmon migration routes by creating unnaturally deep waters immediately off of the shore. About a third of the waterfront was also located under piers, making the water too dark for the salmon to swim under.

Ideally, you can build habitats for people and for fish, said Stuart Munsch, a fishery biologist working for NOAAs Northwest Fisheries Science Center. Education is also really important. People who visit the waterfront might not know about the ecosystem beneath their feet, but Elliott Bay is traditionally a nursery habitat for juvenile salmon to mature, making it an area crucial to protect.

The new seawall mitigates the problems of the water being too deep and too dark. Water is made more shallow by installing shelves on the side of the seawall, called marine mattresses, and the wall itself is textured to look something like a climbing wall, making a more accommodating surface for fish food to grow. Glass blocks are used to pave walkways above ground, and this allows light to pass through to the water.

UW researchers helped provide the science to create the habitat of the seawall, said Jeff Cordell, a member of the UW research team which tested the potential panels for the seawall.

Youre never going to have the seawall constructed in a way that includes all the complexities a natural habitat does, Cordell said. Yet the Seattle seawall takes many more steps to recreate the original food chain.

All of these measures dramatically improve the area for salmon. EarthFix recently published a video providing a good look at the new seawall features.

I really love working in urban systems, said Jason Toft, a restoration ecologist and research scientist at the UW. Urban and ecological systems can work together.

Any urban coastline or major port will affect the natural habitats in some way, but because this concept is relatively similar in any area, it is important that Seattle is making these steps. Basic aspects of well-lit, shallow waters can be applied in different cities around the world to restore nursery grounds for juvenile fish.

At lowtide, the seawall is visible from the piers. July is the peak month for salmon migration, so those visiting the waterfront should be able to see the juvenile fish.

Seattle continues to be a groundbreaking city when it comes to ecological restoration. Ideally the strides that UW researchers make with Seattles seawall can be applied to cities around the world, and this type of restoration can continue.

Reach reporter Brooke Manningat science@dailyuw.com.Twitter: @brook1052

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Seattle's new seawall - Dailyuw