With temperatures soaring into the 80s and 90s and several months with less rain than the region historically gets, it’s understandable if the topic of flooding is far from the minds of area residents.
For policymakers, though, it has been an active summer for planning and funding flood mitigation and habitat preservation and improvement work.
The Chronicle sat down with Chehalis Basin Board (CBB) member J. Vander Stoep who explained some of the current actions the board is taking to further its combined goals of reducing flooding while also preserving local habitats.
While residents are used to floods, an observed increase in flood size over the past few decades has spurred the CBB to action.
The five largest flood events in the Chehalis Basin occurred within the last 36 years, including the devastating 2007 flood.
To combat the rise in flood frequency and severity, the CBB has now completed 39 flood damage reduction projects, 56 aquatic species habitat restoration projects and three integrated projects at a combined cost of $96 million so far.
Vander Stoep explained that despite the work they’ve accomplished so far, there is still a lot left to do when it comes to flood mitigation and habitat preservation.
One of the largest projects in the works is the continued pursuit of a water retention dam on the Chehalis River near Pe Ell.
“There have been hundreds of dams built in the Pacific Northwest over the past 150 years, and a lot of the old ones are fish blockers. They’re just concrete blocks on the river. They usually have a reservoir, usually have hydro-power and some do provide flood protection. The issue, though, is that they’re bad for fish. They can’t get through and it blocks off habitat,” said Vander Stoep.
The flood retention facility planned to potentially be built just south of Pe Ell would create a flood water storage reservoir during major storms.
Flood retention facilities are still essentially dams, but with passageways for fish built into them so they aren’t cutting off habitats for the fish.
Vander Stoep stated the reason for choosing that specific area is because it receives the highest amount of rain compared to the regions surrounding it.
“Average rainfall in Chehalis/Centralia is approximately 35 inches a year. You get up to Pe Ell where it’s higher (elevation) and it’s around 70 inches a year. Here (in higher elevations of the Willapa Hills), 120 to 130 inches a year, and about 40% to 60% of the water that ends up in Grand Mound (during floods) comes from the area south of Pe Ell,” Vander Stoep said.
Flooding isn’t the only issue being addressed in that area though.
In the CBB’s Aug. 4 meeting, Dr. MaryLouise Keefe, a member of the Chehalis River Basin Flood Control Zone District mitigation team, stated the team is concentrated on a number of issues including fish habitat access.
“Habitat access is opened up by removing barriers, a pretty simple concept,” said Keefe, “we have proposed to open up access to 42.5 miles of suitable salmon habitat.”
There are 228 fish passage barriers in the upper Chehalis basin right now, and if at least 75 are removed it could easily open up the 42.5 miles of habitat Keefe and her colleagues are aiming to restore, she said.
She went on to state the area will see an overall ecological lift by helping provide more cool water during the hot summer months.
Culvert replacement has been overseen by the district as well, mainly to replace old, small culverts with much larger ones that can handle the flooding seen in the region. Wetlands are also projected to double in size after the planned mitigation efforts are completed.
One last issue Keefe addressed was the future of the basin beyond the mitigation efforts currently being implemented. Monitoring and adaptive management are also being implemented.
“Nobody really knows what climate change is going to make this river (the Chehalis River) look like, but we have to have something in place so we can react and we can ensure that the function that is intended by these mitigations are maintained,” Keefe said.
The CBB has also recently addressed a number of budget issues. In a July 7 board meeting, members discussed plans to allocate funds reserved for 2021-2023 flood damage reduction and aquatic species habitat restoration projects while reallocating leftover unobligated funds from 2019-2021.
There are a total of 10 proposed projects and requests, with the grand total cost for all of them being $13.92 million.
Some of the projects include the Experimental Skookumchuck Chinook Salmon Study, which is getting $365,000 in funding; the proposed Airport Levee Project, which is getting $1.85 million in funding; local Flood Authority projects, which are getting $778,000 in funding; the state Route 508 Lewis County Erosion Management Project, which is getting $150,000 in funding; and the Chehalis Basin Stream Gage Master Plan Update, which is getting $75,000 in funding.
The total amount of unobligated funds from 2019-2021 is roughly $3.3 million, according to a memo from the Chehalis Basin Strategy. The board decided to use $2.5 million of unobligated funds toward the Fry Creek Pump Station with another $425,000 in funding going to erosion management.
