Deep Lake
St. Louis County, Minnesota73 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Deep Lake. Here is what has been measured.
- Impaired · Mercury
- 50 ft max depth
- Public access
- Limited data
Deep Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 17.2 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Maximum depth: 50 ft. Surface area: 73.13 acres.
Minnesota DNR's Standard Survey on July 24, 2023 caught 0.33 walleye per gill net at Deep Lake. DNR survey details →
Deep Lake is a 73-acre lake in St. Louis County, Minnesota with a maximum depth of 50 feet. Overall water quality is declining over recent sampling years. The lake supports 10 documented fish species including black crappie, bluegill, and hybrid sunfish. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-08-04. Methodology: how these readings are compared.
What Deep Lake is good for
From access and monitoring records, not editorial picks.
- Clear water17.2 ft of visibility
- Fishing10 species recorded
- Deep water50 ft surveyed max depth
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Deep Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Deep 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 Deep Lake
These are the measurements Minnesota PCA publishes for Deep Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 17.2 ft down. Phosphorus 12 µg/L. Chlorophyll-a 2.5 µg/L. TSI 39.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 17.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 12µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 2.5µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 39 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Deep Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on July 24, 2023 caught 0.33 walleye per gill net at Deep Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Deep Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2023-07-24 (Standard Survey).
7 surveys on file · most recent 2023-07-24 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Largemouth Bass | 9.23 | 10–15 in 2023-07-24 | 0.95 lb |
| Bluegill | 8.64 | 3–7 in 2023-07-24 | 0.1 lb |
| Hybrid Sunfish | 3.29 | 3–8 in 2023-07-24 | 0.18 lb |
| Yellow Perch | 2.89 | 6 in 2023-07-24 | 0.11 lb |
| Northern Pike | 2.11 | 10–25 in 2023-07-24 | 3.41 lb |
| Pumpkinseed | 2.00 | 8 in 2023-07-24 | 0.16 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.
Largemouth Bass
Bluegill
Hybrid Sunfish
Yellow Perch
From the 2023-07-24 survey
Deep Lake is a 73-acre lake located two miles south of Gilbert. There is a public access with an earthen boat ramp located near the south end of the lake off CR 97. The access is relatively small, with limited space for parking or turning around. Deep Lake has relatively steep drop-offs, especially along the north…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Deep Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — DeepFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Deep (1763)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — DeepFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
50 ft
Surface area
73 acres
Shoreline
1.7 mi
Littoral zone
45%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
4 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,385 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Deep Lake
Compare lakeside cabins, hotels, and vacation rentals near Deep 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 Deep Lake
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Follow Deep Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Deep Lake
Water quality readings over time
2 seasons of samples on record (2022–2024). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
EPA Impairment Status
Deep 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 MN69-0666-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Deep Lake
Where is Deep Lake?
- Deep 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 Deep Lake?
- Deep Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 17.2 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Maximum depth: 50 ft. Surface area: 73.13 acres.
Is Deep Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Deep Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
How deep is Deep Lake?
- Deep Lake has a maximum depth of 50 feet. The lake covers 73.13 acres.
What fish are in Deep Lake?
- Fish species found in Deep Lake include black crappie, bluegill, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow perch. Deep Lake is located in St. Louis County, Minnesota.
What did the DNR fisheries survey find at Deep Lake?
- Minnesota DNR's Standard Survey on July 24, 2023 caught 0.33 walleye per gill net at Deep Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Deep Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Deep Lake?
- Public access to Deep Lake is listed as yes on the lake record. 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.
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Where this data comes from
5 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA5 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- 2120 B ~ Color in Water by Visual Comparison
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