Merrill Lake Depth Map & Fishing Spots (WA)

Hatch outlook

Callibaetis (Speckled Dun)Active window

Typical here: Aug 15 – Sep 15 · the smaller fall brood

nymphthe hours before the midday emergence — nymphs rise off the weed tops in a vertical zigzag that can take hours — sources split between slow 2–4 inch strips with long pauses and a quicker steady retrieve; carry both speeds
dunmidday, roughly 11am into early afternoon
spinnermid-to-late-morning falls

Trout browse the weed-bed edges knocking nymphs loose, then cruise the flats sipping duns at midday — the marquee western lake mayfly.

The midday emergence puts cruisers over weed flats in under 20 ft: a casting bubble with a #14 Callibaetis nymph retrieved dead-slow with pauses is the honest match. Between hatch hours, small spoons and #1 inline spinners along the weed edges and drop-offs pick off the same fish.

The event happens over weed flats and weed-bed edges in 20 ft of water or less

Chironomids (stillwater midges)Active window

Typical here: May 1 – Oct 31

nymphearly morning, start of the day — fish the bloodworm ON the bottom — 4–6 inches off the mud before the emergence starts
pupathe cool morning hours are prime — as the emergence builds, slide the pupa up to 12–15 inches off bottom under the indicator; a little wind chop does the jigging

Concentrates by DEPTH BAND and mud type, not a fixed spot: roughly 20–25 ft in spring, deeper midsummer, in against the feeder creeks in summer heat, 5–25 ft in fall. Match the band.

This one translates almost perfectly: a slip float with a 1/64–1/100 oz midge-pattern jig set 4–15 inches off bottom over a mud flat, dead-sticked with the chop doing the work. Depth control is everything — no moving lure imitates a hanging pupa; the float rig IS the technique.

The event happens over open mud flats alongside weedlines, channels and basin edges; feeder-creek mouths in summer heat

Water boatman fall flightsActive window

Typical here: Aug 25 – Oct 10 · peaks on crisp, bright fall days after the first cold snap

adultmiddday-ish on calm, sunny fall days — the fishable moment is the splashdown: boatmen dive in headfirst trailing an air bubble and make repeated trips back to the surface — a fly or lure that dives nose-first on the drop imitates exactly this

Takes are seldom subtle — trout ravage boatmen as they hit the water and during their subsurface runs.

Tailor-made for hardware: a small 1/16 oz silver-bellied spoon or jig cast AT the rings of a splashdown sinks headfirst exactly like the natural — twitch-pause it back through the top few feet. On flight days fan-cast the shallow weed margins.

The event happens over near-shore shallows, weed beds and shoal margins on calm sunny fall afternoons

Grasshoppers (east-side summer)Active window

Typical here: Jun 15 – Sep 30

adultall day in high summer, best when afternoon wind knocks bugs onto the water

Pulls fish to the windward grassy banks and edges for months — fish the bank the wind blows ONTO.

The friendliest crossover of the summer: on lakes, drift the windward bank with a bubble-and-foam-hopper — the bubble's splash doesn't hurt a hopper presentation. On rivers, the same rig dead-drifted along the undercut grass banks, or small gold spinners under the banks between rises.

The event happens over grassy banks, undercut edges and windward shorelines

Next on this water

Damselfly migration · forageMay 15 – Jul 31 · in ~9 months

Recommendations come from depth structure and seasonal species behavior. Treat them as a starting point, not a guarantee. Contours here are interpolated from real agency depth surveys (state DNR / USACE). Never use for navigation. Always check local regulations.

Loading depth chart…

Recent catches at Merrill Lake

Shared by DepthScout anglers. Exact spots stay private, always.

No shared catches here yet — be the first.Log a catch from the map above and share it to put Merrill Lake on the board.

Fishing Merrill Lake: what the data says

413-acre lake near Cowlitz County. The lake tops out around 77 ft. The depth chart is built from real state fisheries GPS surveys, so the humps, channels and drop-offs you see are measured, not guessed. Species by species, here's what the data says the year looks like.

Merrill Lake maps at 413 acres behind 4.1 miles of shoreline. With a 1.5 development index there's bank structure worth casting at, in moderation. Littoral water — the productive band under ~15 ft — makes up 12% of this chart. Tip to tip the water measures near 1.9 mi with a 0.5-mi widest point. Cowlitz County claims this one. Its nearest charted neighbour, Battle Ground Lake, is 21 mi to the southwest.

Brook Trout fishing at Merrill Lake

Spring brook trout on Merrill Lake hold shallow, usually 2 to 15 ft. They move out to 10 to 30 ft in summer and finish the year down in 3 to 20 ft. Put Creek inflow first on the milk run — an inflow / creek mouth near 6 ft that grades prime for spring. The feeding windows run early morning and the evening. The summer box starts with a small spoon fished deep or a trolled lake-clear wobbler + worm.

Season	Depth	Best window	Start at	Go-to baits
Spring	2 to 15 ft	dawn & dusk	Creek inflow (6 ft)	Small inline spinner (gold), Tiny spoon
Summer	10 to 30 ft	dawn & dusk	Creek inflow (20 ft)	Small spoon fished deep, Trolled lake-clear wobbler + worm
Fall	2 to 15 ft	midday & dawn	Creek inflow (6 ft)	Small spoon (orange), Spinner
Winter	3 to 20 ft	dawn	Creek inflow (6 ft)	Small jigging spoon, Tungsten jig + plastic

Brown Trout fishing at Merrill Lake

Spring puts brown trout in skinny water — 3 to 25 ft is the zone. As the season builds they drop to 25 to 60 ft, wintering in 5 to 35 ft. Spring brown trout concentrate at Creek inflow, a prime-rated inflow / creek mouth around 6 ft. Warm-month bites cluster around after dark and early morning. A spoon at the thermocline or a deep stickbait (night) covers the summer program.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 25 ft	dawn & dusk	Creek inflow (6 ft)	Stickbait off planer boards (shallow), Small spoon along mud lines
Summer	25 to 60 ft	night & dawn	Break off the point (75 ft)	Spoon at the thermocline, Deep stickbait (night)
Fall	5 to 30 ft	dusk & dawn	Creek inflow (6 ft)	Jerkbait over gravel, Casting spoon
Winter	5 to 35 ft	dawn	Creek inflow (6 ft)	Jigging spoon, Small stickbait (slow)

Rainbow Trout fishing at Merrill Lake

Early season rainbow trout use the shallows, holding in 5 to 20 ft. Summer is an 8 to 30 ft game here, winter an 8 to 40 ft one. The chart's best answer is Creek inflow — inflow / creek mouth, 6 ft, prime for spring. Best bite is early morning and the evening. Tie on a dodger + spoon (deep troll) or a flutter spoon and you're in the game.

Season	Depth	Best window	Start at	Go-to baits
Spring	5 to 20 ft	dawn & dusk	Creek inflow (6 ft)	Inline spinner (silver), Small spoon
Summer	8 to 30 ft	dawn & dusk	Creek inflow (20 ft)	Dodger + spoon (deep troll), Flutter spoon
Fall	10 to 35 ft	dawn & dusk	Main-lake point (12 ft)	Casting spoon, Jerkbait over shoals
Winter	8 to 40 ft	dawn	Creek inflow (20 ft)	Jigging spoon, Tube jig (white)

Notable structure

8 pieces of structure are mapped here — Deep basin, around 77 ft, is the deepest of them.

Deep basin: deep basin, around 77 ft
Break off the point: drop-off, around 75 ft
Creek inflow: inflow / creek mouth, around 20 ft
Back-bay flat: feeding flat, around 16 ft
Shallow bay flat: feeding flat, around 13 ft
Main-lake point: point, around 12 ft
Creek inflow: inflow / creek mouth, around 6 ft
Old creek channel: creek channel, around 3 ft

Public access & boat ramps

Boat launch — ramp
Boat launch — ramp

Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. Confirm conditions and fees locally before you launch.

Merrill Lake fishing regulations

Season dates, license requirements, and size and bag limits for Washington waters are set by the Washington Department of Fish and Wildlife — and special regulations can apply to Merrill Lake specifically, so confirm the current rules before you fish.

Check the official Washington fishing regulations →

Common questions

How deep is Merrill Lake?

Merrill Lake is about 77 ft (23 m) deep at its deepest point. The depth chart here comes from real state fisheries GPS surveys, so the contours reflect measured depths.

What fish are in Merrill Lake?

Anglers target brook trout, brown trout, rainbow trout on Merrill Lake.

Where is the best fishing spot on Merrill Lake?

Creek inflow is the top-rated area: an inflow / creek mouth in about 6 ft of water that rates prime for brook trout in spring. Every other rated spot, per species and season, is on the map above.

When is the best time to fish Merrill Lake?

For brook trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.

What are the fishing regulations for Merrill Lake?

Fishing on Merrill Lake is regulated by the Washington Department of Fish and Wildlife. Check the official Washington regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.

Nearby waters

Battle Ground Lake 21 mi · Horseshoe Lake 24 mi · Silver Lake 26 mi · Riffe Lake 28 mi · Cowlitz River 33 mi · Lacamas Lake 33 mi · Round Lake 34 mi · Council Lake 35 mi · Mineral Lake 44 mi · Packwood Lake 50 mi · Clear Lake 51 mi · Elbow Lake 52 mi

See how Merrill Lake stacks up: best rainbow trout lakes in Washington · best brown trout lakes in Washington · best brook trout lakes in Washington

Browse all Washington fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.