Jackson-Frazier Wetlands Restoration

“Zoom out and take a landscape perspective,” says Jeff Baker, Stewardship Director of the Greenbelt Land Trust. As humans, this isn’t always easy to do. We tend to see parcels of properties more readily than patches of habitat. But for more than a decade, work by Greenbelt, Benton County Parks & Natural Areas, and the City of Corvallis has sought to change this in order to preserve and enhance important wetland features on the northeast edge of town. 

Benton County Parks & Natural Areas will begin a restoration project at Jackson-Frazier Wetlands this summer. Three main goals lay at the center of their efforts: to restore wetland hydrology, to restore vegetation diversity, and to increase environmental education and outreach opportunities. 

Jackson and Frazier creeks drain the hillsides of MacDonald-Dunn Forest, flowing together just northwest of the Jackson-Frazier Wetlands. On the path from their headwaters to the valley floor, they carry clay sediments. When the water reaches flatter topography, it slows down and the sediments settle out. Over time, this has created the circumstances necessary for the wetlands to form. 

During the wet winter months, the clay swells, preventing water from percolating into those deeper sediment layers below. Instead, the water stays on the surface, sometimes forming ponds. During our summer droughts, the clay dries, shrinks, and cracks open, allowing the surface water to slowly recharge the groundwater. 

However, extensive ditching that first occurred in the 1930s dramatically changed the functioning of the wetlands. While surface waters of the wetlands previously flowed back into Frazier Creek in the northeast before reaching the Willamette River, they then were pushed to drain into Stewart Slough in the southeast. The last private landowner of the wetlands exacerbated the problems this ditching might have caused by deepening them further in 1984, without securing the necessary permits from the county, state, or federal governments. More than three decades later, you can still see water flowing through the ruts created as machinery drove across the easily molded clay to dig these ditches. 

The county now sits with the task of undoing this damage in order to achieve their restoration goals. Adam Stebbins, park superintendent with the county and the manager of the Jackson-Frazier Wetland long-term restoration project, says that the county will smooth away the ruts left behind and “make more depressional areas so there’s more water storage on site, rather than it going to the ditches.…it’ll be a decent increase in storage longer into the season.” 

Additional restoration activities will stop the encroachment of shrubs, trees, and invasive species. Since time immemorial, the Kalapuya Tribe maintained the Willamette Valley as a prairie through prescriptive burning practices. This prevented shrub and tree encroachment on the wetland, as well as encouraging the growth of important foods. However, in the 1830s, Euro-Americans introduced disease to native populations and claimed their land through the federal Donation Land Claim Act, effectively ending burning practices. 

Over the next century, tree encroachment at the Jackson-Frazier Wetlands was prevented to some extent by cattle grazing and harvesting native hay. However, between the time it took for the last private landowner to increase ditching and for the county to assume title after foreclosure in 1990, fast-growing shrubs and trees moved in. 

In response, the county plans to mow down and apply herbicides to the unwanted vegetation. “That disturbance will help the native seed bank, plus we’ll come back in the fall after the 2019 season and re-seed heavily with forb species. Right now, we have dominant grasses and shrubs and limited diversity of forb species out here,” says Stebbins. Without human management, the remaining wet prairie would secede to shrub and forested wetland types. This would cause a decrease in available habitat for federally listed threatened and endangered native plant species—including Bradshaw’s lomatium, Nelson’s sidalcea, and Kincaid’s lupine—of which each have their own unique pollinator, such as the similarly listed Fender’s blue butterfly. 

On top of the natural secession pressure these species are currently facing, non-native, invasive reed canary grass degrades the wetland even more. Reed canary grass, with origins in Europe, grows throughout the year, shooting up to six feet in the summer, making it incredibly difficult for native species to compete. In addition, it forms a thick mat of roots, similarly difficult to penetrate by other plants, or for humans to remove by hand.

Removing invasive species and re-contouring the wetlands is intensive work, but the community can get involved in restoration activities within a specific area designated for this purpose. In this part of the park, “we’ll do plantings, weeding—we could have demonstration burning on a small scale,” Stebbins says. This will help to continue a legacy of volunteerism here, considering that the entire length of the 3,400 foot boardwalk was built by the hands of lay people in 1996. 

Originally considered to meet Americans with Disabilities Act requirements, the boardwalk allowed people from all walks of life to access the park. Today, requirements have changed, and the boardwalk has aged, leading to some debate amidst the restoration planning on how best to address this beneficial manmade feature. Stebbins explains, “we have a choice to make—do we keep replacing sections and investing public funds and donations into that or do we say okay we’ve got to redo this whole thing to maximize the funding we have and then maybe we could get a grant to replace part of it. Who knows…to take all this out, to put something that’s modern and permitted out here, it’d be pricey…that’s something that we need to look at as we go forward with our planning.”

Stebbins also worries about future development within the upper reaches of the watershed, “if that upper area ever increased in density then there’d be a lot more management that’s going to have to happen of the stormwater.” 

Further development on the neighboring Good Samaritan Hospital property is planned. But, the Greenbelt Land Trust and City of Corvallis jointly conserve Owens Farm, located just across Highway 99 from the wetlands, and named after the settler family that retained the property for several generations until 2002. 

While increased floodwater storage capacity is one of the goals of the county’s work, it could not be sustained “if Owens Farm wasn’t purchased by Greenbelt and it was used for some other purpose,” says Baker, “if it was developed for housing, that would increase runoff into the streams faster, going into the wetlands faster, and filling them up faster.” This would be particularly concerning because “when you do get flooding down there it is because the wetlands got full and then it comes out into the neighborhoods,” such as what many experienced in the winter of 2012. 

In addition to preventing flooding in adjacent neighborhoods, “from a habitat perspective, larger patches of habitat usually have more benefits for the species that live there. Owens Farm by itself is 95 acres, but if you add in Jackson-Frazier that increases the total acres that the wildlife can use there to about 300 acres. It decreases the fragmentation and creates more connected habitats to have these two properties together,” says Baker. 

Unlike the county-owned Jackson-Frazier Wetlands, Owens Farm is currently only accessible to the public via guided tours by Greenbelt. Yet, its value in floodwater storage and habitat connectivity cannot be emphasized enough. “The habitats that we have on that property are almost endangered in the Willamette Valley…most of the Willamette Valley has been developed for agriculture and what’s not been developed for agriculture has been developed for residential and urban areas. So the original habitats that are here are a very small proportion of what they were,” says Baker. 

Stebbins would agree: “Jackson-Frazier Wetland is one of the only ones of this size and quality in the Willamette Valley. Usually these were ditched, drained and built on, so it’s important to retain it and restore it, to conserve it for the future generations to understand what these habitats look like and how they function and the benefit they provide.”

Perhaps underlying these statements is an understanding that pre-settler land management practices created valuable ecosystem services that ought to be sustained today. With this recognition in mind, the restoration work underway seeks not just to restore the land, but to restore human understanding of it as well. 
 
 
By Ari Blatt 
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