Flat Lake
McHenry County, North Dakota278 acresView mapDirections
No nutrient or algae sampling on record from ND DEQ for this lake.
Flat Lake in McHenry County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Surface area: 278 acres.
Flat Lake is a 278-acre lake in McHenry County, North Dakota.
Source: EPA Water Quality Portal sampling records, NDDEQ. Methodology: how these readings are compared.
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Flat Lake is safe to swim in today is a call for the North Dakota Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Flat Lake
These are the measurements ND DEQ publishes for Flat Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. TSI undefined.
Ask about Flat Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
278 acres
Shoreline
3.9 mi
No bathymetric survey has been published for Flat Lake, so its depth is not documented here.
Stays via Stay22
Stays near Flat Lake
Compare lakeside cabins, hotels, and vacation rentals near Flat Lake in McHenry County, North Dakota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Flat Lake
Prices for Oct 16–18, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at North Dakota’s top lakes →
Follow Flat Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Flat Lake
Nearby Lakes in McHenry County
Frequently asked questions about Flat Lake
Where is Flat Lake?
- Flat Lake is a lake in McHenry County, North Dakota. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Flat Lake?
- Flat Lake in McHenry County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Surface area: 278 acres.
Is Flat Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Flat Lake across LakeQuality
More lakes in North Dakota
Other Lakes in North Dakota
Where this data comes from
Measurements for Flat Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Depth, fish, and access data from North Dakota Game & Fish