Flood Impacts on Salmon, Cultural Resources

Natural Resources

Flooding is a natural process and important for salmon habitat formation. Historically, abundant salmon and diverse habitat provided natural resilience to flooding, but the legacy and ongoing impacts to salmon habitats have left them much more vulnerable to extreme events. Given the fragile status of our salmon populations, the Tribe’s Natural & Cultural Resources Department is concerned about the impacts of the recent, historic flood event.

High river flows risk washing out salmon eggs and displacing rearing juveniles, unless they are able to access slow-moving water. Depending on how the flood waters recede, fish can also get stranded on the floodplain. Additionally, emergency response to protect people and property after major flooding can include rapid installation of riprap and bulldozer construction, which can often damage salmon habitat. If that wasn’t enough, flooding creates a toxic slurry of contamination, introducing chemicals, gasoline, oil, paint, manure lagoon storage, and more into the river.

“After all the restoration work the Tribe has done, it feels like two steps forward, and ten steps back,” says Natural & Cultural Resource Director George Swanaset, Jr. days after the November flood. The flood appears to be one of the top flood events on record for the North and Middle Fork and the Nooksack River at Ferndale, which poses a significant risk to salmon. Over the years, the Tribe has worked with co-managers Lummi Nation and WDFW to evaluate impacts of flooding on local salmon populations. This information guides restoration and resource protection efforts before disaster strikes.

View of the Tribe’s downstream of Hutchinson Reach Restoration Project on the South Fork near a section known locally as the “dozer hole.” Credit: Lindsie Fratus-Thomas.

“We see in the Nooksack River and elsewhere, years with high annual peak flows are associated with low salmon survival,” says Treva Coe, Habitat Program Manager for the Nooksack Tribe. “Our river restoration efforts focus in part on building resilience to floods.” For example, she cites goals to reconnect floodplains in order to restore floodplain rearing and flood refuge habitat for salmon and restoring side channels that provide spawning habitat less vulnerable to salmon redd (nest) scour – or washing out — during high water events. Floodplain reconnection can also benefit people by increasing flood water storage, which can reduce flooding downstream.

However, rapid response to flood recovery can be detrimental to fish habitat.  “Often, the emergency response to flooding, while important to protect people and property, can damage habitat in the long term,” says Coe. “That’s why we work with our local government partners preemptively to develop programs, policies, and projects to reduce flood risk in a way that is supportive of salmon recovery.”

Visible water marks on cedar trees at a private property where the Tribe’s Homesteader Reach Restoration Project is proposed on the South Fork Nooksack.

Floods bring powerful, erosive forces. Natural log jams can break up during flood events, often reforming downstream. The Tribe’s restoration projects involve construction of large engineered log jams designed to provide the same habitat benefits as natural log jams, but with greater safety and predictability. Treva Coe says engineered log jams are designed to be stable and resilient to channel changes, including both channel migration and avulsion, which is the rapid abandonment of a river channel and the formation of a new one. 

“After every flood, we are eager to get out and survey our restoration projects, just as our local public works staff survey bridges and roadways for flood damage,” Coe says. Nooksack staff, including watershed restoration coordinators Lindsie Fratus-Thomas and Eric Stover, and geologist Michael Maudlin, surveyed project sites both by helicopter and by land following the flood (as access and flows allowed), trying to assess cost and damage to restoration efforts.

“We have seen some damage to individual log jams as a result of past floods, though the vast majority of log jams we have constructed have remained stable and largely intact.” The Tribe has invested considerable resources in salmon habitat restoration in the past 15 years and hopes that some state-of-emergency funding will be made available to restore not just “gray infrastructure” (roads, bridges, etc.) but also the “green infrastructure” – habitat and habitat restoration structures – critical to sustaining important treaty resources.

Even with project infrastructure securely in place, a flush of naturally derived river sediment can be detrimental to salon during major flood events. The Nooksack Water Resources Program reports nearly 60 temperature monitoring locations, five stream gaging stations, and four continuous turbidity monitoring stations throughout the watershed were at risk of washing out. Generally, the data collected with this equipment helps monitor the river and determine water quality conditions effecting salmon.

Helicopter view of one of the Lummi Tribe’s upper South Fork Restoration Projects (ELJ’s on left side of river and at the head of the island).

“Sediment transport is especially harmful to salmon and salmon habitat during flood events,” says Jezra Beaulieu, Nooksack Water Resources Specialist “Fine sediment in particular can affect salmon by burying and suffocating their redds, affecting their hunting and feeding behavior, or by abrading their gills, which can then lead to infection.” The department says that water quality technicians Tom Cline and Rich Auguston have been visiting sites and assessing damage to their equipment. “So far, the turbidity and sediment monitoring sites on the mainstem Nooksack River at Nugent’s Corner, and at Saxon Road on the South Fork, were washed out in the flood, in addition to a number of temperature sensors throughout the watershed,” Beaulieu says.

At the same time, Cultural Resources staff inspect erosion impacts on cultural resources such as traditional villages, ceremonial sites, and Tribal cemeteries. After a major flood event in 2014, Tribal members Francisco Sanchez, Tom Cline, and Richard Auguston found a 300-year-old cradle buried in the silt at the base of a root wad of an upturned tree while surveying the Nooksack River by boat. For over five years the Burke Museum in Seattle worked to restore the ancient cedar root cradle and used carbon dating to estimate the age. The 300-year-old Nooksack cradle is on display at the Burke Museum.

If you find anything of cultural interest that may be related to the Nooksack Indian Tribe, please report findings to Trevor Delgado and the Nooksack Cultural Department at (360) 306-5759.

Photo credits for this story: Lindsie Fratus-Thomas, Nooksack Watershed Restoration Coordinator.

Back side of an ELJ located within the Tribe’s downstream of Hutchinson Reach Restoration Project on the South Fork. Note the grass indicates water flowed over the bank.
View of one of the Lummi Tribe’s upper South Fork restoration projects (ELJ’s on left side of river and mid-channel.
In 2014, the 300-year-old Nooksack cradle was found in the riverbank after a high river event. It is now on display at the Burke Museum in Seattle. Credit: Trevor Delgado.