County hears Army Corps update: SRS crest‑raise, sediment concerns and limited federal funding options

Cowlitz County staff on Tuesday presented the U.S. Army Corps of Engineers' 2025 river survey and modeling results and urged the board to consider targeted requests for Corps continuing‑authority funding.

"They presented the results from the 2025 river survey and modeling," said Susan, a county staff member who briefed the board on the Corps slides. She said the Corps' monitoring shows that return‑period protection varies across leveed reaches: Longview and Kelso remain at high return‑periods in recent years, while Castle Rock and Lexington have trended downward since 2022 and are approaching their authorized protection levels.

The briefing described an ongoing 10‑foot crest raise at the Sediment Retention Structure (SRS) intended to retain more sediment and improve water clarity, and noted that the contractor has mobilized with a construction window of up to two years and an internal goal of finishing in 2026.

Susan told commissioners the Corps estimated current sediment retention effectiveness at the SRS at roughly 13 percent, meaning the majority of incoming sediment currently passes the structure. "That was the statistic they gave us," she said. County staff explained that much of the coarse sediment carried from the upper Toutle and Toutle–Cowlitz system continues downstream and deposits through the Cowlitz and Columbia reaches, contributing to local channel aggradation in places.

Staff also reminded the board that the Corps treats 'level of protection' (LOP) for levied areas and structural levy integrity as separate programs: the hydrologic modeling that generates return‑period figures focuses on how leveed reaches perform during design storms, whereas levee inspection and structural repairs are handled under a different Corps authority and different funding streams.

Beyond the technical update, staff urged the board to consider pursuing project‑specific letters of interest under the Corps' Continuing Authorities Programs (CAPs). Susan reviewed several CAP options and typical cost‑share rules: Section 14 (emergency streambank/shoreline protection) generally requires a feasibility study and is limited to replacing in‑kind at the same location (typical federal/local shares reported as roughly 65/35); Section 204 (beneficial use of dredged material) and Sections 206/1135 (aquatic ecosystem restoration) can support habitat restoration and beneficial placement of dredge spoils but have eligibility limits tied to authorized navigation projects or to degradation caused by federal works.

"Section 204 could be used for beneficial use of dredge materials," she said, but cautioned that the program's navigation‑project requirement may limit applicability for some bank stabilization efforts. Staff reported FY2026 program funding levels they obtained from Corps contacts: roughly $1 million for Section 14, $18 million available for Section 204, $500,000 for Section 206 and about $3 million for 1135, with the caveat that eligibility and local matching obligations remain key constraints.

Commissioners asked staff to follow up with Corps contact Omar Ortiz on project‑specific feasibility questions — particularly for shoreline stabilization at county priority sites (referred to as LT1 in the briefing), bank stabilization and dredge‑spoil beneficial use at the mouth of the Toutle/Cowlitz system — and to prepare letters of interest where warranted.

Staff additionally noted the Corps' recently issued final environmental impact statement for Columbia River dredging and asked whether the board wanted to submit comments; staff offered to read the EIS and report back in time to meet the public comment deadline.

What happens next: county staff will prepare project‑specific questions and potential letters of interest for the Corps CAP programs and return with recommendations on which feasibility studies to pursue and what local funding would be required to match federal shares.