Chehalis Basin Flood Authority briefs Cosmopolis council on pumps, warning system and proposed flow‑through dam

Scott Venture, staff to the Chehalis River Basin Flood Authority, told the Cosmopolis City Council on Nov. 20 that the authority has focused since 2008 on projects that reduce flood hazard while protecting fish and local infrastructure.

"We can't stop flooding," Venture said. "We can take steps to help with the risk and with post‑flood resiliency." He listed roughly $55 million the authority has deployed on local projects and said about 100 on‑the‑ground projects have been completed in the basin.

Venture highlighted a range of efforts. Small, targeted investments included 25 farm pads to protect livestock (total cited about $600,000) and flood vents installed in 10 homes (average cost about $8,500) to reduce flood insurance costs for homeowners. Larger projects ranged from log‑jack bank stabilization — a roughly $2 million installation that Venture said averted a potential $40 million replacement of a wastewater plant — to pump stations such as the Raymer Street Basin pump (about $1.3 million) that Venture said protected roughly $72 million in assets and moved 51 million gallons in a recent flood event.

Venture said the authority is pursuing geographically based planning in complex areas such as Chehalis and Centralia and is increasingly focused on coordinated solutions for the lower basin. "We think the projection right now is about $50 million for pumps in the lower basin in Aberdeen and Hoquiam," he said, describing that investment as necessary to protect an estimated $1 billion in assessed value.

The presentation included a roughly five‑minute informational video on a proposed flow‑through dam design that, according to the video, would hold back water only during rare extreme events while allowing fish passage in normal conditions. Venture said the design intends to reduce downstream peak flows without permanently blocking fish migration; he added the project is under state and federal review.

Venture also described a basin flood‑warning system of stream gauges and telemetry operated in partnership with USGS, NOAA, tribes and state agencies. He said sign‑ups for gauge alerts have grown from a few hundred in 2014 to about 4,200 users and that the authority hopes to reach 5,000.

Council members and audience participants asked whether the authority handles stormwater infiltration; Venture said the authority focuses on floodwaters and that local stormwater management remains the responsibility of city public works. He said Aberdeen, Hoquiam and Cosmopolis public works directors are drafting a joint flood and pump plan to align technology and rate structures.

The presentation emphasized the regional nature of the work and the authority's reliance on collaborative governance. Venture said the Chehalis Basin board and the Office of Chehalis Basin in the Department of Ecology administer projects and that the program has received sustained legislative funding over multiple biennia.

Next steps mentioned to the council included making presentation materials available, signing up for gauge alerts and continued coordination on the joint lower‑basin pump plan. The authority indicated installation of a new tide gauge at the port in coming months; staff noted about a year of data would be needed before the gauge fully informs local tidal forecasts.

— Reporting from the Cosmopolis council meeting on Nov. 20.