Merwin
Dam in Cowlitz County, Washington · Lewis River · forms Lake Merwin
Height
313 ft
95 m (NID height)
Length
1,250 ft
381 m
Completed
1931
Lake Merwin today
228.00 ft
7 days ▼ 2.00 ft
Normal storage
422,000 acre-ft
Much below normal for the date
Reservoir level measured Oct 23, 2026, 10:00 AM PDT. Full level page →
Facts
- Purposes
- Hydroelectric; Fish and Wildlife Pond; Recreation
- Dam type
- Arch
- Structural height
- 313 ft
- Owner
- Private
- Maximum storage
- 422,000 acre-ft
- Surface area
- 3,921 acres
- Hydraulic height
- 230 ft
- Drainage area
- 726 sq mi
- Spillway
- Controlled
- Army Corps district
- Portland District
- NID ID
- WA00149
Facts from the U.S. Army Corps of Engineers National Inventory of Dams, record updated Aug 26, 2026. Search NID ID WA00149 at nid.sec.usace.army.mil. Project website.