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B

Pine Lake

St. Louis County, MinnesotaMesotrophic

Pine Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

Mesotrophic conditions dominate at Pine Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Pine Lake is a shallow lake at 14 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 450 acres, Pine Lake fits the Minnesota median for monitored lakes, with 4.1 miles of shoreline. Among the 187 graded lakes in St. Louis County, Pine Lake sits at rank 54, above the county median.

No invasive species are currently listed at Pine Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Pine Lake, one of 8 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2020-09-14. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 7.5 ft. Phosphorus level: 15.5 µg/L. Trophic State Index: 46.

MetricValueGrade
Water Clarity (Secchi Depth)7.5 ftC
Phosphorus15.5 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)46Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth14 ft
Surface Area450.07 acres
Shoreline Length4.1 mi
Littoral Zone100%
Public AccessYes

Fish Species

bluegill,hybrid sunfish,northern pike,pumpkinseed,rock bass,walleye,white sucker,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Pine Lake (14-day solunar calendar)

→ Is it safe to eat fish from Pine Lake? (mercury & PFAS guide)

Pine Lake fishing regulations (limits, seasons, special rules)

Location

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County Ranking

Ranked #54 of 187 lakes in St. Louis County

Cleaner Lakes Within 30 Miles

Pine Lake holds Grade B. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in St. Louis County

Compare Pine Lake With Nearby Lakes

DNR Fisheries Survey Summary

5 surveys on file from MN DNR Fisheries. Most recent: 2017-06-26 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluegill16.920.26 lb
Yellow Perch9.680.21 lb
Pumpkinseed5.050.15 lb
Northern Pike4.611.94 lb
Walleye3.181.88 lb
White Sucker1.162.83 lb

CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.

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

187 fish · 18 in · 2017-06-26
8141012345678

Yellow Perch

36 fish · 59 in · 2017-06-26
126056789

Pumpkinseed

57 fish · 47 in · 2017-06-26
351804567

Northern Pike

62 fish · 1042 in · 2017-06-26
1050trophy 361012141618202224262830323436384042

From the 2017-06-26 survey

Pine Lake is in Ecological Lake Class 16, which consists of 38 lakes in northeast Minnesota that are large, shallow, and have bog-stained and soft (unmineralized) water. Lake bottom substrates along the shoreline are 30% sand, 30% gravel, 20% boulder, 17% rubble, and 3% muck. Aquatic plants grow to a depth of 4 ft;…

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Pine Lake. 3 reports on file.

EPA Impairment Status

Pine Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN69-0001-00 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Lake details from Minnesota DNR LakeFinder

Most recent sample: 2020-09-14

Monitoring stations: 1