Linn Lake
Chisago County, Minnesota177 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Linn Lake. Here is what has been measured.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- Eurasian watermilfoil
- 15 ft max depth
Linn Lake in Chisago County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 68.5 µg/L. Chlorophyll-a (algae): 43.4 µg/L. Maximum depth: 15 ft. Surface area: 176.99 acres.
Minnesota DNR's Standard Survey on August 21, 1978 caught 13.50 northern pike per gill net at Linn Lake. DNR survey details →
Linn Lake is a 177-acre productive, nutrient-rich eutrophic lake in Chisago County, Minnesota with a maximum depth of 15 feet (6-foot average). Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 29 other monitored lakes in Chisago County, Linn Lake ranks #30 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
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. Linn Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Linn 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 Linn Lake
These are the measurements Minnesota PCA publishes for Linn Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2 ft of visibility. Phosphorus 68.5 µg/L. Chlorophyll-a 43.4 µg/L. TSI 67.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 68.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 43.4µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 67 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Linn Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Linn Lake typically sits around 72°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 78°F) and coldest in May (about 66°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (66°F) to its warmest (78°F).
Typical surface water temperature by month, from 41 field readings (2011–2025) via the EPA Water Quality Portal. See the full Linn Lake water temperature breakdown →
Minnesota DNR's Standard Survey on August 21, 1978 caught 13.50 northern pike per gill net at Linn Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Linn Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1978-08-21 (Standard Survey).
1 survey on file · most recent 1978-08-21 (Standard Survey)
48 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 245.34 | 0.12 lb | |
| Brown Bullhead | 46.59 | 0.26 lb | |
| Bluegill | 20.33 | 0.38 lb | |
| Hybrid Sunfish | 13.75 | 0.31 lb | |
| Northern Pike | 8.41 | 0.74 lb | |
| Pumpkinseed | 1.67 | 0.38 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.
From the 1978-08-21 survey
When compared to respective state medians, the present fish population status of Linn Lake is as follows. The Blk Bullhead was extremely high at 164 times the state median and the Brn Blhd was very high at 52 times the median. The N Pike was very high at 13.50 per set or 5 times the median and ranged from 11 to 16…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Linn Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LinnFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
15 ft
Average depth
6 ft
Surface area
177 acres
Shoreline
3.2 mi
Littoral zone
100%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Elevation
886 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Linn Lake
Compare lakeside cabins, hotels, and vacation rentals near Linn Lake in Chisago 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Linn Lake are listed below.
Top-rated places to stay near Linn Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fishing Linn Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Worsening+1.5 µg/L/yr6 years
Chlorophyll-a
Improving-2.31 µg/L/yr6 years
EPA Impairment Status
Linn 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: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN13-0014-00 · Official waterbody report
Nearby Lakes in Chisago County
Frequently asked questions about Linn Lake
Where is Linn Lake?
- Linn Lake is a lake in Chisago County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Linn Lake?
- Linn Lake in Chisago County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 2 ft visibility. Phosphorus: 68.5 µg/L. Chlorophyll-a (algae): 43.4 µg/L. Maximum depth: 15 ft. Surface area: 176.99 acres.
Is Linn Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Linn Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Linn Lake?
- Linn Lake typically sits around 72°F at the surface in September, from 41 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Linn Lake?
- Linn Lake has a maximum depth of 15 feet and an average depth of 6 feet. The lake covers 176.99 acres.
What did the DNR fisheries survey find at Linn Lake?
- Minnesota DNR's Standard Survey on August 21, 1978 caught 13.50 northern pike per gill net at Linn Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Linn Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Linn Lake?
- Public access to Linn Lake is listed as no on the lake record, so confirm before you make the trip. 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 Linn Lake across LakeQuality
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Where this data comes from
93 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA93 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
- 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