Dam Removed Carefully in Steps to Protect Fish and Habitat

For decades, an obsolete dam at Balm Grove, 12 miles upstream from the confluence of Gales Creek and the Tualatin River, has acted as a major fish passage barrier for aquatic life in the Tualatin River Watershed. Its removal in September 2022 opened up nearly 35 miles of prime habitat to threatened species such as the winter steelhead and Pacific lamprey, a major step forward in a larger statewide effort in fish habitat restoration. 

A multi-step process ensured the safety of local species and protected the health of the surrounding ecosystem. First, crews dug a diversion channel to temporarily reroute the creek. Culverts were installed so construction crews could access the work site.

Once the diversion channel had been graded and secured with erosion control, a cofferdam (an enclosure built within a body of water to allow the enclosed area to be pumped out) was erected, and 25% of the creek’s flow was diverted into the channel. Starting with a slow flow helped to minimize the dirt moving downstream while also signaling to fish that it was possible to swim upstream through the new channel.

The stream’s diversion marked the first time since 1936 that fish had been able to successfully get around the dam. Crews were heartened to see that salmon almost immediately started to move upstream.

“Instant gratification is rare in ecological restoration, but we got to experience it by helping Clean Water Services remove a dam that has been impeding migratory fish passage since the ‘30s,” Matt Koozer of Biohabitats notes. “Just like that, miles of habitat opened up for species like coho salmon, Pacific lamprey, and winter steelhead along Gales Creek.”

Once construction of the cofferdam was complete, the creek’s flow was completely diverted. Crews salvaged the remaining fish and removed the dam.

A coalition of Tree for All partners, together with Biohabitats, manage the site’s rehabilitation. Next summer, partners will insert logjam structures to provide shelter and habitat to native species. They will also revegetate the site with native plants and excavate the nearby floodplain to ensure that the creek is able to rise from its channel and saturate the adjacent cottonwood forest.

“Dam removals are the single most important thing we can do to restore our rivers and streams,” says Scott McEwan, executive director of the Tualatin River Watershed Council. “The removal of the dam at Balm Grove is a major win for our environment, and it couldn’t have been done without the coordination and commitment of our partners.”

Stay tuned here for more updates! To learn more about the history of this project, you can read the Balm Grove case study.

Many thanks to our partners on this project: Clean Water Services, the Intertwine Alliance, Metro, Northwest Steelheaders, Oregon Department of Fish and Wildlife, Trout Unlimited, Tualatin River Watershed Council, Tualatin Riverkeepers, and Tualatin Soil and Water Conservation District.

October 2022 Community Events

Take advantage of the volunteer opportunities offered by our partners this month!

City of Hillsboro/Jackson Bottom Wetlands

SOLVE

Friends of Tryon Creek

Friends of Trees

Tualatin Riverkeepers

The Wetlands Conservancy

Tualatin Hills Park & Recreation District

September 2022 Community Events

Take advantage of the volunteer opportunities offered by our partners this month!

City of Hillsboro/Jackson Bottom Wetlands

  • Wednesdays in September, 12:00pm: Nature at Noon

    For a full list of City of Hillsboro/Jackson Bottom Wetlands events, click here.

SOLVE

Tualatin Hills Park & Recreation District

Tualatin Riverkeepers

TFA Partners Help to Build Defenses Against the Emerald Ash Borer

On June 30, 2022, the Oregon Department of Agriculture (ODA) and Oregon Department of Forestry (ODF) confirmed the first infestation of the Emerald Ash Borer in Oregon. Native to Asia, the Emerald Ash Borer (EAB) was first identified in the United States twenty years ago, and has since spread to three dozen states. The EAB is deadly to all species of ash tree and is now considered to be “the most destructive forest pest in North America,” according to the ODA.

Our partners at Clean Water Services (CWS) and Tualatin Soil and Water Conservation District (TSWCD), in conjunction with the City of Forest Grove, have already taken steps towards mitigating the effects and spread of the EAB infestation. Their efforts have included mapping existing ash trees, planning for replacement plantings, and setting traps for the insects. CWS staff have also emphasized the importance of nurturing a diverse range of native plants, which can provide shelter, food and habitat in the event one species is threatened.

Here are some ways that you can help to slow the spread of the Emerald Ash Borer:

August 2022 Community Events

Take advantage of the volunteer opportunities offered by our partners this month!

City of Hillsboro/Jackson Bottom Wetlands

The Wetlands Conservancy

SOLVE

Tualatin Hills Park & Recreation District

Tualatin Riverkeepers