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Updated August 2026 · All 12 lakes with a surveyed depth

Deepest Lake in North Dakota: Lake Sakakawea (180 ft)

Lake Sakakawea is North Dakota's deepest lake at 180 ft, per the North Dakota Game and Fish Department. Lake Oahe backs up into south-central North Dakota, so it is technically a North Dakota water, but its 205-ft maximum depth is at Oahe Dam near Pierre, South Dakota. The North Dakota reach is far shallower -- during the 2000-2008 drought Oahe receded out of North Dakota entirely, back into the historic Missouri River channel. Mapped and ranked below: the 12 deepest of 12 North Dakota lakes with a surveyed maximum depth.

Map · 12 ranked lakesTap a pin for its lake
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Nutrient and algae readings on recordNo reading on record#1 in this rankingPins are this ranking's lakes at their surveyed locations.

Top 12 Deepest Lakes in North Dakota (by max depth)

#LakeCountyMax depthMean depthSurface area
1Cain LakeRolette30 ft—78 ac
2Lake JessieGriggs15 ft—528 ac
3Fresh LakeKidder12 ft—201 ac
4Island LakeRolette12 ft—1,887 ac
5Willow LakeKidder11 ft—508 ac
6Clear LakeMcIntosh10 ft—198 ac
7Gullys SloughRichland10 ft—654 ac
8Sweetwater LakeRamsey8 ft—1,597 ac
9Silver LakeBenson8 ft—563 ac
10Long LakeMcLean8 ft—211 ac
11Bentley LakeMcHenry7 ft—206 ac
12Jim LakeStutsman6 ft—1,521 ac

Sources and method

  • Max and mean depth: state natural-resources agency lake surveys and USACE National Inventory of Dams reservoir records. Surveyed depths only; modeled estimates are never ranked. A dash means the survey did not record a mean.
  • Deepest lake: Lake Sakakawea, 180 ft, per the North Dakota Game and Fish Department, 2022. Lake Sakakawea lake page (its record carries no surveyed depth, so it is not in the table)
  • Readings: clarity, phosphorus and chlorophyll-a from the agency's own sampling, shown as reported. Depth is not a water-quality reading.
  • Map pins: the 12 table rows with surveyed coordinates. No other lakes are plotted.

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Frequently Asked Questions

What is the deepest lake in North Dakota?

Lake Sakakawea, at 180 ft, in McLean, Mercer, Dunn, Mountrail, McKenzie, Williams County. Lake Oahe backs up into south-central North Dakota, so it is technically a North Dakota water, but its 205-ft maximum depth is at Oahe Dam near Pierre, South Dakota. The North Dakota reach is far shallower -- during the 2000-2008 drought Oahe receded out of North Dakota entirely, back into the historic Missouri River channel. Source: North Dakota Game and Fish Department, 2022.

How are lake depths measured?

Maximum depth is the deepest point at full-pool water level, from state agency bathymetric surveys and, for reservoirs, dam-design records. The ranking uses surveyed depths only, never modeled estimates. Everyday water level can sit below the surveyed figure during drawdowns or drought. Mean depth, the average across the whole basin, is listed where a survey recorded it.

Why are some North Dakota lakes so much deeper than others?

Lake depth depends on how the lake formed. Glacial lakes (common in MN, WI, MI, NY) were carved by ice sheets and can exceed 200 ft. Reservoir lakes (common in IA, MO, OK, KS) are shaped by river valley depth at the dam site — typically 50-150 ft at the dam, much shallower upstream. Flooded mine pits can be deeper still. Oxbow lakes and pothole lakes formed by river meandering or glacial pitting tend to be shallower, usually under 30 ft.

Does deeper mean cleaner?

Not directly, but deeper lakes tend to be cleaner on average. Depth creates thermal stratification in summer, isolating cold deep water from surface algal blooms. Deep lakes also resist nutrient resuspension from wind-driven sediment mixing. That said, many deep lakes still suffer from impairment if the watershed loads heavy phosphorus — each lake's page carries its nutrient readings and EPA impairment status.

What's the average depth of North Dakota lakes in this ranking?

Across the 12 deepest North Dakota lakes, the average maximum depth is 11 ft and the median is 10 ft (Gullys Slough). This is the top of 12 lakes with a surveyed depth, so it is biased toward deep lakes; the typical North Dakota lake is shallower.

Where to stay near North Dakota's deepest lakes

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