State’s Chehalis Basin office outlines six long‑term flood and fish strategy options, including flow‑through dam and Skookumchuck Dam choices

The Office of the Chehalis Basin on Wednesday briefed Thurston County commissioners on six long‑term strategy options to reduce flood damage and restore aquatic habitat across the Chehalis Basin, including a proposed “flow‑through” dam, a package of local levees and alternatives for the Skookumchuck Dam.

The Office’s director, Jim Zenk, said the office — housed in the Washington Department of Ecology — is charged by the Legislature to develop a strategy that balances near‑term flood protection and long‑term aquatic species restoration. “Our primary goal is to aggressively pursue flood damage reduction and aquatic species restoration within the basin,” Zenk said.

Why it matters: the Chehalis Basin is the state’s second‑largest basin and supports timber, agriculture and other economic activity; the basin has seen declining salmon runs and increasingly frequent flooding that has caused major damage in the past. The board and basin partners are weighing multi‑decade investments that could affect communities in Thurston County and neighboring jurisdictions.

Most of Zenk’s presentation described a suite of six options that technical teams are evaluating. On the structural side, one option centers on a proposed flow‑through dam upstream of the basin that would remain open during normal…