The dramatic tale of 100 years of flood mitigation efforts in the Chehalis Basin will peak next November when local flood experts report to Gov. Jay Inslee and recommend — or don’t recommend — continuing progress with construction of a water retention structure on the upper Chehalis River.
In the 2013-15 capital budget, flood mitigation efforts were awarded $28.2 million; $5.6 million was allocated specifically for determining the permit feasibility, engineering safety and mitigation requirements of building a dam.
To be prepared for that critical juncture next November, local flood experts need concrete data — fast.
Planned work includes engineering analysis of alternatives, including fish passage requirements, hydrology and hydraulic analyses to define inundation and protection levels, quantified environmental impacts to, and mitigation requirements for, fish, water quality and sediment transport, updated costs and benefits of the alternative designs.
But even that list of work is general.
The work on the ground — such as that being done by the Washington Department of Fish and Wildlife — is completed meter by painstaking meter.
Mara Zimmerman, the research scientist who designed Fish and Wildlife’s current project, said that broad data must be collected and analyzed before the effects of a dam can be estimated.
“You’re going to change the flow of the river and therefore you’re going to change the habitat,” Zimmerman said. “Floods, from a Fish and Wildlife perspective, destroy but also create — that’s sort of a natural process that happens, and when you alter that, you’re altering the process of destroying and creating.”
“We’re trying to understand now where fish are in the river what habitats are important to them,” she said.
A team of four Fish and Wildlife technicians, led by project manager John Winkowski currently are working their way down the Chehalis River, counting steelhead, chinook and coho while measuring the depth and the width of the river.
The team on Monday deployed two technicians into the river to snorkel and collect data.
Every 200 meters, the snorkelers gathered with the rest of the team — who followed behind, collecting other information — and reported the fish tallies they had marked on their waterproof slates, worn like arm guards.
The team will work 200 meters at a time, 5 kilometers a day until it reaches the end of its 100-kilometer journey.
Their data will become more meaningful when combined with other information, including GIS maps and detailed water temperature data collected via a three-day flyover, currently in progress, according to Zimmerman.
Several fish tagging operations, operated by both Fish and Wildlife and the Chehalis Tribe, will help create a fuller picture of fish movement.