Nichols Lake
St. Louis County, Minnesota419 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Nichols Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- 31 ft max depth
- Public access
- Limited data
Nichols Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.1 ft visibility. Phosphorus: 20.5 µg/L. Chlorophyll-a (algae): 6.4 µg/L. Maximum depth: 31 ft. Surface area: 418.67 acres.
Minnesota DNR's Targeted Survey on August 11, 2025 caught 0.20 walleye per fyke net at Nichols Lake. DNR survey details →
Nichols Lake is a 419-acre productive, nutrient-rich eutrophic lake in St. Louis County, Minnesota with a maximum depth of 31 feet (8-foot average). The lake supports 12 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in St. Louis County, Nichols Lake ranks #19 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2020-09-15. Methodology: how these readings are compared.
What Nichols Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing12 species recorded
- Ice seasonIce-out around Apr 15
- Deep water31 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Nichols Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Nichols Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Nichols Lake
These are the measurements Minnesota PCA publishes for Nichols Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5.1 ft. Phosphorus 20.5 µg/L. Chlorophyll-a 6.4 µg/L. TSI 50.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 20.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 6.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 50 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Nichols Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Nichols Lake typically sits around 62°F at the surface in September. Summer average is about 68°F. Usually warmest in Jul (about 70°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (55°F) to its warmest (70°F).
Typical surface water temperature by month, from 35 field readings (2019–2019) via the EPA Water Quality Portal. See the full Nichols Lake water temperature breakdown →
Minnesota DNR's Targeted Survey on August 11, 2025 caught 0.20 walleye per fyke net at Nichols Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Nichols Lake’s water-quality measurements separately. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
8 surveys on file from MN DNR Fisheries. Most recent: 2025-08-11 (Targeted Survey).
8 surveys on file · most recent 2025-08-11 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 9.76 | 3–9 in 2025-08-04 | 0.18 lb |
| Largemouth Bass | 8.81 | 5–16 in 2025-08-04 | 1.29 lb |
| Northern Pike | 2.55 | 17–26 in 2025-08-04 | 1.7 lb |
| Black Crappie | 2.54 | 4–10 in 2025-08-04 | 0.21 lb |
| Yellow Bullhead | 2.48 | 9–11 in 2025-08-04 | 0.85 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Bluegill
Largemouth Bass
Northern Pike
Black Crappie
From the 2025-08-11 survey
A targeted survey of nearshore fish species in Nichols Lake was conducted on August 11th-13th, 2025, by Lake Biological Monitoring and Assessment (LBMA) program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing, mini-fyke nets, and seining with a 50-foot or…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Nichols Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — NicholsFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Nichols (1819)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — NicholsFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — NicholsPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
31 ft
Average depth
7.9 ft
Surface area
419 acres
Shoreline
4.9 mi
Littoral zone
86%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
22 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,299 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Nichols LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Nichols Lake
Compare lakeside cabins, hotels, and vacation rentals near Nichols Lake in St. Louis 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.
Top-rated places to stay near Nichols Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Nichols Lake
Ice season
Typical ice-out
Apr 15
Earliest Mar 29, 2010 · Latest May 1, 2008
Most recent ice-out
Apr 12
2021
7 observations · Minnesota PCA ice records
EPA Impairment Status
Nichols Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN69-0627-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Nichols Lake
Where is Nichols Lake?
- Nichols Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Nichols Lake?
- Nichols Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.1 ft visibility. Phosphorus: 20.5 µg/L. Chlorophyll-a (algae): 6.4 µg/L. Maximum depth: 31 ft. Surface area: 418.67 acres.
Is Nichols Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Nichols Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Nichols Lake?
- Nichols Lake typically sits around 62°F at the surface in September, from 35 EPA Water Quality Portal field readings (2019–2019). That is a typical value for the month, not a live reading.
How deep is Nichols Lake?
- Nichols Lake has a maximum depth of 31 feet and an average depth of 7.9 feet. The lake covers 418.67 acres.
What fish are in Nichols Lake?
- Fish species found in Nichols Lake include black crappie, bluegill, brown bullhead, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Nichols Lake is located in St. Louis County, Minnesota.
What did the DNR fisheries survey find at Nichols Lake?
- Minnesota DNR's Targeted Survey on August 11, 2025 caught 0.20 walleye per fyke net at Nichols Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Nichols Lake’s water-quality measurements separately. Catch rate is not a swim clearance and is not a weekly bite report.
When does Nichols Lake thaw?
- Nichols Lake typically has ice-out around Apr 15.
Are there boat ramps on Nichols Lake?
- Nichols Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Nichols Lake. Public access is listed as yes.
Can I fish at Nichols Lake?
- Nichols Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Nichols Lake across LakeQuality
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Species activity outlook by water temperature and season
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Where to stay at Minnesota's top lakes, each with its readings
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Where this data comes from
15 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA15 samples · 2020
Analytical methods
- Field measurement/observation, generic method
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate