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Natural Glacial•Montana Lakes•Lake, Flathead County

Flathead Lake, Montana: Map, Depth, Size & Information

Comprehensive hydrographic guide to Flathead Lake featuring verified USGS & USACE water statistics, interactive topographic mapping, shoreline facilities, boating ramps, and game fisheries.

Directions
Surface Area
122,880 acres
497.3 km²
Max Depth
370 feet
112.8 m
Elevation
2,893 feet
882 m ASL
Shoreline
161 miles
259 km
Coordinates
47.883°, -114.117°
GPS WGS84
Verification
Official Data
2026-03-08
Live Hydrographic & Conditions Telemetry

Flathead Lake Live Water Level Status & Wind Conditions

Reservoir Hydrography
Water Level Status & Capacity
Current Water Elevation
2,893.28 ft
Normal Full Pool: 2,893.00 ft
Normal Conservation Pool
Difference from Full Pool
+0.28 ft(above)
Reservoir Waterline & Storage Capacity96% of Conservation Pool
0%
25%
50%
75%
100% Full
Full Pool: 2,893.00 ft
24h Change: -0.08 ft / 24hEst. Volume: 19,346,227 acre-ft
Inflow Rate
6,170 cfs
River tributaries
Dam Outflow
5,259 cfs
Hydro & spillway
Water Temp
52°F
Surface layer
Water Clarity
20.1 ft
Secchi disc depth
Hydrologic balance: Current net flow is +911 cfs (Gaining volume). Water level is falling at 0.08 ft per day.
Atmospheric & Surface
Live Wind & Wave Simulator
Caution for Small Craft
Nautical Wind Compass Rose
NESW
W 273°
17 mph
Gusts: 27 mph
Blowing from W (273°) at 17 mph
Surface Wave Conditions1.5 ft wave height
Moderate Chop (1.0 - 2.0 ft)
Whitecap Chop & Swell
Barometer
29.88 inHg
Steady pressure
Solunar Bite
Active Feeding
High game fish bite
Hourly Forecast Timeline Scrubber:12 PM • 17 mph W
Calculate Water Level & Volume ChangesModel acre-feet storage loss, shoreline recession, and drought reserve projections for Flathead Lake.
Open Calculator

Interactive Map of Flathead Lake

47.8833° N, 114.1167° W|Get Directions
Centroid Coordinates: 47.8833° N, -114.1167° WOpen Directions in Maps

Where is Flathead Lake?

Flathead Lake is located in Lake, Flathead County in the state of Montana, at geographical coordinates 47.8833° North latitude and 114.1167° West longitude. The water body lies at a surface elevation of approximately 2,893 feet (882 meters) above mean sea level.

Nearby Cities & Distances

Polson
1 miles away
Bigfork
1 miles away
Kalispell
9 miles away
Missoula
65 miles away

About Flathead Lake

Crystal clear water of Flathead Lake Montana with Mission Mountains in background
Natural Glacial • Glacial Moraine LakeVerified 2026-03-08

Flathead Lake is the largest natural freshwater lake by surface area west of the Mississippi River in the contiguous United States (slightly larger than Lake Tahoe in surface area, though shallower). Framed by the Mission Mountains to the east and the Salish Mountains to the west, Flathead Lake is renowned for its crystalline water clarity, Wild Horse Island State Park (home to wild horses and bighorn sheep), and Flathead sweet cherry orchards along the shore.

Hydrographic Classification:

Flathead Lake is categorized as a Glacial Moraine Lake. Its designated primary authorized uses include Recreation, Hydropower (Séliš Ksanka Ql'ispé Dam), Irrigation, Wildland Conservation.

Activities & Recreation

Sport Fishing

Flathead Lake is known for its resident game fish species. Common targets include:

Lake Trout (Mackinaw)Yellow PerchLake WhitefishBull TroutCutthroat Trout
Boating & Watersports

Popular watercraft activities permitted across regulated channels:

BoatingSailingCherry PickingIsland ExplorationTrophy Trout FishingKayakingCamping

Boat Ramps, Marinas & Public Parks

Marinas (4)

  • •Flathead Harbor Marina (Lakeside)
  • •Somers Bay Marina
  • •Bigfork Marina
  • •Polson Bay Marina

Public Boat Launches (4)

  • •Lakeside Public Boat Ramp
  • •Somers Boat Launch
  • •Bigfork Launch Ramp
  • •Polson City Park Ramp

Parks & Recreation (3)

  • •Wild Horse Island State Park
  • •Flathead Lake State Park (Wayfarers, Finley Point, Yellow Bay)
  • •Glacier National Park (45 miles north)

Boating Safety, Wake Zones & Aquatic Regulations

• Speed & Wake Buffer Zones:

A mandatory 100-to-200-foot no-wake zone is enforced around all public boat launches, designated swimming areas, private docks, and moored vessels. Vessel operators must maintain idle speed in narrow coves and bridge passes.

• Safety Gear & AIS Protocol:

Coast Guard-approved Type I, II, or III PFDs are required for all vessel occupants. To prevent aquatic invasive species (quagga mussels, hydrilla), boaters must adhere to Clean, Drain, and Dry inspection procedures prior to launching.

Seasonal Fishing Patterns for Flathead Lake

Spring (March – May)Pre-Spawn & Spawn

Game fish move into sheltered secondary coves, shallow flats (4–12 ft depth), and creek mouths as surface temperatures climb into the 50s and 60s. Target submerged timber, riprap, and emerging vegetation with spinnerbaits, suspending jerkbaits, and soft plastics.

Summer (June – August)Thermocline & Main Basin

Predators retreat to deep underwater humps, main river channel ledges, and thermocline layers (20–45 ft). Peak activity shifts to dawn, dusk, and night trolling. Use deep-diving crankbaits, spoons, drop-shots, and downrigger spreads.

Autumn (Sept – November)Fall Turnover & Feeding Blitz

Cooling weather triggers lake turnover and intense schooling feeding. Bass, trout, and walleye push baitfish into primary points and pocket coves. Fast-moving topwater plugs, lipless crankbaits, and swimbaits produce explosive strikes.

Winter (Dec – February)Deep Suspension & Ice

Fish consolidate around deep wintering holes (40–80+ ft) or under safe solid ice on northern waterways. Slow finesse presentations—vertical jigging spoons, blade baits, and live bait rigs—dominate the cold-water season.

Flathead Lake Statistics & Hydrography

MeasurementImperial ValueMetric Equivalent
Surface Area122,880 acres497.3 km²
Maximum Depth370 feet112.8 meters
Average Depth164 feet50.0 meters
Water Surface Elevation2,893 feet above sea level882 meters
Shoreline Length161 miles259 km
Lake ClassificationNatural Glacial (Glacial Moraine Lake)
GPS Coordinates47.8833° N, 114.1167° W

Frequently Asked Questions about Flathead Lake

8 verified answers
Is Flathead Lake bigger than Lake Tahoe?+
In surface area, yes! Flathead Lake covers approximately 191 square miles (122,880 acres), slightly larger than Lake Tahoe’s 190 square miles. However, Lake Tahoe is far deeper and holds over 3.5 times more water by volume.
What is Wild Horse Island?+
Wild Horse Island is a 2,160-acre primitive state park inside Flathead Lake, accessible only by boat. It preserves a herd of wild horses, bighorn sheep, mule deer, and bald eagles.
How deep is Flathead Lake in Montana?+
Flathead Lake reaches a verified maximum depth of 370 feet (113 meters), with an estimated mean operating depth of approximately 164 feet (50 meters). The lake bathymetry features typical natural glacial bottom topography with distinct drop-offs, deep submerged channels, and shallow littoral zones that support aquatic vegetation and forage species.
What is the surface area, shoreline length, and elevation of Flathead Lake?+
At normal conservation pool, Flathead Lake covers approximately 122,880 surface acres (about 192.0 square miles or 497.3 km²) at an elevation of 2,893 feet above sea level. The shoreline extends for 161 miles (259 km) throughout Lake, Flathead County, featuring numerous sheltered coves and bays.
What game fish can you catch in Flathead Lake?+
Anglers on Flathead Lake target Lake Trout (Mackinaw), Yellow Perch, Lake Whitefish, Bull Trout, Cutthroat Trout. Peak fishing occurs during spring spawning runs in shallow bays and submerged timber, followed by summer deep-water trolling near thermocline depths and structural humps. Autumn brings aggressive feeding activity along windward points.
Can you boat on Flathead Lake and where are the public ramps?+
Yes, recreational boating is permitted on Flathead Lake. Public boat launch facilities include Lakeside Public Boat Ramp, Somers Boat Launch, Bigfork Launch Ramp. Full-service marinas including Flathead Harbor Marina (Lakeside) and Somers Bay Marina offer slip rentals, marine fuel, and boat repair services. Boaters must adhere to state navigation laws, maintain required life jackets and safety gear, and respect posted no-wake zones near docks, coves, and designated swimming beaches.
Who manages Flathead Lake and are there campgrounds or parks nearby?+
Flathead Lake is managed and monitored in coordination with Montana Fish, Wildlife & Parks & USGS Montana Water Science Center. Lakeside recreation areas and campgrounds include Wild Horse Island State Park, Flathead Lake State Park (Wayfarers, Finley Point, Yellow Bay), Glacier National Park (45 miles north). Visitors can take advantage of developed campgrounds with tent and RV hookups, scenic hiking trails, day-use picnic areas, and boat launch access.
Where does the data for Flathead Lake come from and how is it verified?+
All hydrographic statistics, water surface elevation gauges, surface acreage measurements, and bathymetric soundings for Flathead Lake are cross-referenced from authoritative federal and state geospatial databases, primarily Montana Fish, Wildlife & Parks & USGS Montana Water Science Center and the USGS National Hydrography Dataset (NHD). Records undergo programmatic sanity verification and were last verified on 2026-03-08. Detailed ingestion pipelines, calibration procedures, and agency citations are published on our Data Methodology page (/methodology/).
Review Full Data Methodology & Verification Guidelines
Authoritative Data Source: Montana Fish, Wildlife & Parks & USGS Montana Water Science Center
Last verified: 2026-03-08 • Record ID: flathead-lake-mt
View Official Source

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