Free Peoples Lake
Benson County, North DakotaView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↓ down from A at the last regrade
- Eutrophic
- #2 of 5 in the county
- 41 ft max depth
Free Peoples Lake in Benson County, North Dakota has a water quality grade of B (Good). Phosphorus: 27.6 µg/L.
- Typical in August
- 73°F
- Max depth
- ~41 ft est.
- Type
- Eutrophic
- Phosphorus
- 27.6 µg/L
- Trend
- ↑ Improving
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Watch Free Peoples Lake’s letter
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Free Peoples Lake is a productive, nutrient-rich eutrophic lake in Benson County, North Dakota with an estimated average depth of about 41 feet. Water quality is graded B based on 1 sampling years through 2023. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Benson County, Free Peoples Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-05-10. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: B (Good)
No clarity data. Phosphorus 27.6 µg/L. TSI 52. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 27.6 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Free Peoples Lake typically sits around 73°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 73°F) and coldest in May (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 37 field readings (2019–2023) via the EPA Water Quality Portal. See the full Free Peoples Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~41 ft est. |
| Average Depth | ~10 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Dakota has not published bathymetry for Free Peoples Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Free Peoples Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -3.1 µg/L/yr | 2 |
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Free Peoples Lake under Clean Water Act (NPDES) discharge permits.
- Spirit Lake Rural Water System Water Treatment PlantSaint Michael · 2.7 mi away · NPDES ND0031101
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #2 of 5 lakes in Benson County
Nearby Lakes in Benson County
Frequently asked questions about Free Peoples Lake
Where is Free Peoples Lake?
- Free Peoples Lake is a lake in Benson County, North Dakota. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Free Peoples Lake?
- Free Peoples Lake in Benson County, North Dakota has a water quality grade of B (Good). Phosphorus: 27.6 µg/L.
Is Free Peoples Lake safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Free Peoples Lake?
- Free Peoples Lake typically sits around 73°F at the surface in August, from 37 EPA Water Quality Portal field readings (2019–2023). That is a typical value for the month, not a live reading.
How deep is Free Peoples Lake?
- No published bathymetric survey covers Free Peoples Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 41 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Free Peoples Lake across LakeQuality
Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
12 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Spirit Lake Tribal EPA Programs
SPIRITLK12 samples · 2021–2023
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Depth, fish, and access data from North Dakota Game & Fish