Washington lake

Lake Merwin

Cowlitz and Clark Counties, Washington

WDFW lists Lake Merwin at about 3,835.6 acres in Cowlitz and Clark counties near Ariel. Kokanee are the main target, with rainbow trout and tiger muskie also listed.

Air temp Loading current temperature…

Map data © OpenStreetMap contributors.

Current air temperature at Lake Merwin (National Weather Service) ↗

Surface area3,836 acres

Max depth—

Shoreline—

Boat motorsCheck local rules

Species

Fishery rating out of 5.

Kokanee●●●○○

Main target per WDFW

Rainbow Trout●●○○○

Boat launches

3 launch sites. Fees and hours change, so confirm before you go.

Speelyai Bay launchPublic
Operated by PacifiCorp; weekend launch feeDirections ↗
Cresap Bay launchPublic
Operated by PacifiCorp; weekend launch feeDirections ↗
More public accessPublic
See the state agency or lake website for all ramps and feesDirections ↗

Size & creel limits

Minimum size and daily limit for each species in Lake Merwin are published by the state. Look up the current size and creel limits for this lake directly: Washington Department of Fish and Wildlife (2026-27 pamphlet on eRegulations) ↗

Rules change, so confirm current limits with the Washington Department of Fish and Wildlife (2026-27 pamphlet on eRegulations) before you fish.

Bait & tackle nearby

No shops listed yet for this lake. Use the search link below.

Search more bait shops near Lake Merwin ↗

Local tips

Water levels vary; call 800-547-1501 for current reservoir levels.
All bull trout and Dolly Varden must be released.
Shore access is very limited, so plan to fish from a boat.

View on interactive map

Zoom and pan on a street, satellite or terrain map. Red pins are boat launches.

More Washington lakes

Lake Chelan Banks Lake Lake Wallula (McNary Pool) Lake Washington Potholes Reservoir Ross Lake Riffe Lake Lake Entiat All Washington lakes →

Always wear a life jacket and check your state's current regulations before you fish.