SAVING ROXHILL BOG: First, fix ‘the bathtub’

(Images from meeting presentation – above, Roxhill Park and Bog)

By Tracy Record
West Seattle Blog editor

Imagine you want to take a bath – but not only can you not draw enough water to fill the tub, the water you do get keeps draining out.

That’s the problem with Roxhill Bog, experts and advocates believe, and as unveiled at this week’s community meeting, they have a plan that might fix it.

“Might” is the important word here – so they’re going to try an experiment on part of the endangered wetland, which is all that’s left of a 10,000-year-old peat bog that once stretched far beyond the remnant that exists – dry as it is – mostly on the south side of city-owned Roxhill Park.

Wednesday night’s meeting had many of the same participants who gathered more than a year and a half ago – just before the pandemic shut down in-person meetings – to accelerate the effort to keep the bog from being lost forever.

This time, interested and/or involved parties gathered online to talk and hear about what’s been learned and what happens next.

Sharon Leishman of the Duwamish Alive! Coalition opened the meeting and noted the area’s role as the historic headwaters of Longfellow Creek, which she said is having an “amazing year” of coho-salmon returns.

The bog’s place in the Duwamish River ecosystem was then described in detail by Brandon Parsons of American Rivers. “It’s not just about the bog, it’s about the entire watershed” – which ranges across more than 2,600 acres, second-largest watershed feeding the Duwamish. He also recapped his organization’s involvement since 2019, in response to a community call for help. The importance of longrunning community involvement was then underscored by West Seattle/South Park City Councilmember Lisa Herbold, who has been championing the restoration effort.

The heart of the presentation came from Steve Winter of Natural System Design. He explained what they’ve learned about how water moves through the site – some does come in, and you could see that during the recent heavy rains.

But the water doesn’t remain above ground for long. They used wells to check water levels and found it three feet or further below the surface – where it needs to be at the surface year-round to support a true wetland. So to fix it, they have to “significantly reduce the outflow.” Just bringing in more water wouldn’t work, Winter said, without reducing the outflow. They must “repair the bathtub to retain water.”

They believe that can be done by digging and filling a narrow trench to act as a barrier, and they want to test it on one of the bog’s “cells” to see if it works.

It’s experimental and incremental, Winter emphasized, a “pilot project.”

They’re still figuring out what materials would be best for the barrier – something with “very low permeability.” The goal isn’t to trap the water, just to keep it in the bog for longer. “Plug the leak, as it were.” If it works, then they can expand it to other parts of the bog.

But fixing the bathtub’s drainage function isn’t the entirety of the solution. Brenda Gardner of Seattle Public Utilities explained where her department comes in – to “fix the plumbing.” SPU studied ways to reroute water into the bog area. Big challenge, though – the water would have to be treated to some degree, because of runoff’s toxicity. That could be done through swales/bioretention, or through a centralized facility/area.

So why go to all this effort? Landscape architect Danielle Devier of Natural System Design explained that rehydrating the bog will help the park and the surrounding area. She said that 85 percent of those who responded to a survey last year said that local natural areas are “very important” to them. In this one, it’s not just a matter of the peat bog at risk – other features of the park are in jeopardy as the peat (which you might recall had a fire in 2017) continues drying out. Trails and benches are sinking.

As also noted in a breakout discussion, some of the current visibility problems and shrubbery overgrowth in the historic bog area of the park have led to safety concerns – but year-round water in those areas will remove that overgrowth and restore sightlines.

The “stretch goal” for this plan is to get the experimental section of barrier built in next year’s “dry season.” If it can’t be done in time, then the construction would slide to 2023. They’ll continue studying the area in the meantime to ensure they have as much data as possible. As for funding, they have $300,000 in grants received so far, and are aiming for more. Leishman tells WSB that costs are covered for “100% design of the pilot project, including the groundwater block, educational signage, and possibly some construction costs, depending on what construction costs are at the time when it goes out to bid. We are continuing to raise funds to increase the likelihood of construction by 2023.”

P.S. You can see the full slide deck from the meeting (the images used above are just part of it) by going here.

9 Replies to "SAVING ROXHILL BOG: First, fix 'the bathtub'"

  • David November 19, 2021 (5:41 pm)

    When I was a kid. In the late 50’s this area was a swamp and covered in trees year around – it flowed into the land that is now Westwood Village before it was developed. I remember drain pipes going in that were tall enough to walk through when Westwood was being built. My question is how much is it going to cost to get it back to what it was before The City had the bright idea of turning a swamp into a park?

  • HS November 19, 2021 (8:03 pm)

    This is great! I feel like this space gets a bit lost in all the neighborhood news. We are very fortunate to have a peat bog. 

  • OLDtimer November 19, 2021 (10:02 pm)

    Perhaps not relevant, but I recall people planting rice on somewhat terraced hill above where Chase is currently and land filled (around 1964) and Westwood Village drained the bog/swamp on the other side of Barton.   Kids were cautioned re playing in area. I had nightmares of sinking in quicksand.  Ha!  A lot of Waterfront/West Seattle successfully used fill (for added buildable land not so successful for wet lands.  Cost/ benefit analysis as revealed  almost 60 years later… 

  • Friend O'Dinghus November 20, 2021 (12:11 am)

    Hi Old Timer. I used the aerial 1953 photo of the area to create an enlarged version. Basically the center of the image is what is currently Westwood Village. It matches what you describe. Note the unique intersection of SW Henderson and SW Barton for bearings. The Roxhill Park/Bog area is in the square just below that. I find this photo fascinating, but I am confused as to what the building is located in the area above the center square. This would be the SW Athletic Fields/football stadium today, but this was before Sealth HS, or the Community Center/Swimming pool, was built. My question is, what is that large building in this image that is cited exactly where the Community Center/Pool is today? It looks from this photo that the now razed Denny Middle School on 30th Ave SW at Thistle wasn’t even built yet when this photo was taken. Anyone have any added insights to this?

  • DRC November 20, 2021 (9:21 am)

       Fix it and they will come

  • steve_winter November 20, 2021 (10:19 am)

    A big thank you to the WSB for attending the meeting and helping to get the word out on the collective efforts to repair the wetland at Roxhill Park!To Friend O’Dinghus – I suspect that what you are seeing in the photo is the signature of the earthwork associated with what is now the Nino Cantu SW Athletic Center, rather than a building. There appears to have been significant grading and filling in that area, evident by the slopes around the baseball fields (great sledding hill), and the slope that now has the stands of the stadium. Here is a quick snapshot of a hillshade using modern topography that shows the shape of the SWAC:That is my take, but sounds like David and Oldtimer might have some insights from that time, as wellThanks again,Steve Winter

    • Friend O'Dinghus November 20, 2021 (3:22 pm)

      Thanks Steve for the input about the SWAC site. I had erred in thinking that the old Denny Middle School wasn’t in the photo, but according to Wikipedia it opened in 1952. It proves that the photos are indeed difficult to read sometimes. Perhaps they were preparing the site….a built in pool would need a hole dug after all. Much appreciated again. Let’s all save the bog. It looks like it was part of a long watershed from White Center Northwards. It would be a true pity to let this ancient formation go to waste. I can only imagine how fun it must have been as a kid to ice skate on those ponds.

  • AmandaK November 20, 2021 (4:59 pm)

    So great to see all of the efforts made over the last 10 years coming to fruition!  Well done everyone.Thank you!

  • Uncle Jim November 22, 2021 (7:51 pm)

    Denny Junior High was comprised of the three long buildings in the NW corner of the photo.  The Southwest Community Center pool didn’t open until the mid-70’s so it’s unlikely that there was any site preparation going on at the time of this photo.

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