Mountain 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 Mountain 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 Mountain Lake on the board.

Fishing Mountain Lake: what the data says

227-acre lake near San Juan County. The lake tops out around 120 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. The season-by-season read for each species follows, from the map's own numbers.

The drawn water covers 227 acres wrapped in 2.7 miles of bank. At index 1.3 the outline is almost a bowl — read the depth changes, not the shoreline. Roughly 3% of the water is 15 ft or less, the band where the food chain lives. End to end it runs roughly 1.2 mi, about 0.4 mi across. San Juan County claims this one. Its nearest charted neighbour, Sportsmans Lake, is 13 mi to the southwest.

Cutthroat Trout fishing at Mountain Lake

The spring pattern is a shallow one: cutthroat trout in 3 to 15 ft. As the season builds they drop to 10 to 35 ft, wintering in 10 to 40 ft. Time it for early morning and the evening. Summer baits: a trolled spoon (small) or an inline spinner gets it done.

Season	Depth	Best window	Start at	Go-to baits
Spring	3 to 15 ft	dawn & dusk	open water	Inline spinner (silver/gold), Small spoon
Summer	10 to 35 ft	dawn & dusk	open water	Trolled spoon (small), Inline spinner
Fall	5 to 25 ft	dawn & dusk	open water	Casting spoon, Inline spinner
Winter	10 to 40 ft	dawn	open water	Small jigging spoon, Marabou jig

Kokanee fishing at Mountain Lake

Come spring, look for kokanee tight to the bank in 10 to 30 ft. They move out to 30 to 70 ft in summer and finish the year down in 20 to 80 ft. If you only fish one area, make it Deep basin: a deep basin around 120 ft that scores good in spring. Best bite is early morning. A dodger + pink/orange squid on downrigger or a kokanee bug + corn is the honest summer answer here.

Season	Depth	Best window	Start at	Go-to baits
Spring	10 to 30 ft	dawn	Deep basin (120 ft)	Small dodger + squid (pink), Wedding-ring spinner + corn
Summer	30 to 70 ft	dawn	Deep basin (120 ft)	Dodger + pink/orange squid on downrigger, Kokanee bug + corn
Fall	5 to 40 ft	dawn	open water	Dodger + squid (deeper red/purple), Small spoon
Winter	20 to 80 ft	dawn	Deep basin (120 ft)	Small glow jig + corn or maggot, Tiny spoon

Rainbow Trout fishing at Mountain Lake

When the water first warms, rainbow trout slide up into 5 to 20 ft. Summer is an 8 to 30 ft game here, winter an 8 to 40 ft one. Start at Shallow bay flat. It's a feeding flat holding about 12 ft of water and rates good come spring. The feeding windows run early morning and the evening. Keep a dodger + spoon (deep troll) or a flutter spoon rigged through the warm months.

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

Notable structure

Count 5 structure marks on this chart. The deepest, Deep basin, sits near 120 ft.

Deep basin: deep basin, around 120 ft
Shallow feeding flat: feeding flat, around 32 ft
Shallow feeding flat: feeding flat, around 22 ft
Back-bay flat: feeding flat, around 19 ft
Shallow bay flat: feeding flat, around 12 ft

Mountain Lake stocking report

Date	Species	Count	Size
Nov 14, 2025	Cutthroat trout	15,558	—

Source: WDFW fish-stocking reports, retrieved 2026-08-18.

Mountain 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 Mountain Lake specifically, so confirm the current rules before you fish.

Check the official Washington fishing regulations →

Common questions

How deep is Mountain Lake?

Mountain Lake is about 120 ft (37 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 Mountain Lake?

Anglers target cutthroat trout, kokanee, rainbow trout on Mountain Lake.

Where is the best fishing spot on Mountain Lake?

Shallow bay flat is the top-rated area: a feeding flat in about 12 ft of water that rates good for rainbow trout in spring. The map above holds the full rated-spot list for every species and season.

When is the best time to fish Mountain Lake?

For cutthroat 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.

Is Mountain Lake stocked with fish?

Yes — per WDFW fish-stocking reports records, Mountain Lake was most recently stocked Nov 14, 2025 with 15,558 cutthroat trout. The full stocking history is listed above.

What are the fishing regulations for Mountain Lake?

Fishing on Mountain 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

Sportsmans Lake 13 mi · Heart Lake 15 mi · Lake Erie 16 mi · Lake Campbell 18 mi · Pass Lake 18 mi · Cranberry Lake 20 mi · Cain Lake 22 mi · Pender Lake 22 mi, BC · Latimer Pond 28 mi, BC · Blenkinsop Lake 28 mi, BC · Elk Lake 28 mi, BC · Beaver Lake 28 mi, BC

See how Mountain Lake stacks up: best rainbow trout lakes in Washington · best kokanee lakes in Washington · best cutthroat 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.