Norris Lake
Norris Lake in Mahnomen County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.6 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
- Clarity
- 11.6 ft
- Mean depth
- ~13 ft est.
- Type
- Mesotrophic
Next lake in Mahnomen County
Norris Lake is a mesotrophic lake in Mahnomen County, Minnesota with an estimated average depth of about 13 feet. Water quality is graded A based on 2 sampling years through 2025. Compared to the 11 other monitored lakes in Mahnomen County, Norris Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-09. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.6 ft. Phosphorus level: 15 µg/L. Chlorophyll-a: 3.2 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.6 ft | Not graded |
| Phosphorus | 15 µg/L | Good |
| Chlorophyll-a (Algae) | 3.2 µg/L | Good |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Norris Lake
Compare lakeside cabins, hotels, and vacation rentals near Norris Lake in Mahnomen County, Minnesota — 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~13 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Norris 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 Norris Lake
County Ranking
Ranked #6 of 12 lakes in Mahnomen County
Nearby Lakes in Mahnomen County
Frequently asked questions about Norris Lake
What is the water quality grade for Norris Lake?
- Norris Lake in Mahnomen County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.6 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
Is Norris Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Norris Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 3.2 µg/L. Always check local health department advisories before swimming.
How deep is Norris Lake?
- No published bathymetric survey covers Norris Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 13 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Norris Lake across LakeGrade
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Moderate nutrients, good water quality
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Mesotrophic Lakes in Minnesota
Where this data comes from
34 measurements from 2 monitoring stations, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Chippewa Tribe, Minnesota (White Earth Band) (Tribal)
WEARTH_WQX34 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder