Despite being just a few miles from downtown Renton, the isolation of this area, cut off from surrounding neighborhoods by the river to the south and steep cliffs to the north and west, feels a hundred miles away.
The work here is part of a river-wide effort by Forterra, the City of Renton, Seattle Public Utilities, and King County to control invasive knotweed throughout the Cedar River, with the ultimate goal of replacing knotweed stands with healthy forests that improve water quality and provide wildlife habitat. Ron Regis Park has been one of the last major strongholds of the weed where, just a few years ago, it soared above head height and covered almost every square foot of floodplain within the park.
After three years of treatment, only tiny sprouts of knotweed were popping up last summer. This is cause for celebration, but also shows one of the major impacts of knotweed—when knotweed invades an area it out-competes other native plants and prevents understory species or young trees from growing. This part of Ron Regis Park still had its mature trees from years past, but the understory was bare, and there was no younger generation of trees growing up to replace their elders. Years of the infestation had disrupted forest processes, and it was unlikely new native plants would return before another invasive plant took over. We needed to speed up the process.
The season when Pacific Northwest plants most like to be planted is winter—also the season when river flows double, and wading is no longer an option. In the lead-up to the planting day, we searched for possible access points, hiking in from east, north and west, but each time our hopes were dashed when we ended at the top of a cliff or an impassable private property.
Fortunately, a friend of the program and former WCC crew lead, Cary Hofmann, also moonlights as a fishing guide. Early one December morning the WCC crew met Cary down by the river; the crew with bags of willow cuttings, and Cary with his boat. Between the fast-flowing river and the non-motorized boat with only one person to power it, the crew and Forterra staff were skeptical—but, one by one, each person boarded the boat with willows in hand and were safely paddled across the river.
Once safely on the other side, the crew fanned out with hundreds of willow cuttings each, and by the end of the day had installed almost 2,000 willows across the floodplain. Unlike knotweed, willow trees grow deep, strong roots that stabilize soils, and the trunks and branches keep their structure during winter to store and filter flood waters when needed most. These trees also grow extremely quickly. In just a few years, another huge transformation in this landscape can be expected. While the crew and staff will be back next fall to plant conifers and a more diverse mix of shrubs, these willows will fast-track the process of providing habitat, floodwater storage, and filtration to help bring back the functions of this forest.
If you’d like to join in the effort, you can attend an upcoming volunteer restoration event—though there won’t be a water-crossing.