Flat Lake
Flat Lake in McHenry County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 278 acres.
- Area
- 278 acres
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Why Flat Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Flat Lake, no water-quality sampling on record for this lake.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by NDDEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Flat Lake is a 278-acre lake in McHenry County, North Dakota.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled recent years. Grade methodology: LakeQuality methodology.
Watch Flat Lake water quality
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Flat Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay 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
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 278 acres |
No bathymetric survey has been published for Flat Lake, so its depth is not documented here.
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. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Flat Lake?
- Flat Lake in McHenry County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 278 acres.
Is Flat Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Flat Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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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