Birch Lake
Birch Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 18 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Maximum depth: 69 ft. Surface area: 236.31 acres.
- Clarity
- 18 ft
- Typical in August
- 67°F
- Max depth
- 69 ft
- Area
- 236 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
Next lake in Cook County
Birch Lake is a 236-acre cold, clear oligotrophic lake in Cook County, Minnesota with a maximum depth of 69 feet (26-foot average). Water quality is graded A based on 2 sampling years through 2024. The lake supports 3 documented fish species including lake trout, rainbow trout, and smallmouth bass. Public access is available with 1 public boat landing. Compared to the 43 other monitored lakes in Cook County, Birch Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-02. 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)
Crystal clear, you can see 18 ft down. Phosphorus level: 8 µg/L. Chlorophyll-a: 1.9 µg/L. Trophic State Index: 35.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18 ft | Not graded |
| Phosphorus | 8 µg/L | Good |
| Chlorophyll-a (Algae) | 1.9 µg/L | Good |
| Trophic State Index (TSI) | 35 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Birch Lake
Compare lakeside cabins, hotels, and vacation rentals near Birch Lake in Cook 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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Water Temperature
Birch Lake typically sits around 67°F at the surface in August. Summer average is about 63°F. Usually warmest in Jul (about 67°F) and coldest in May (about 48°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 186 field readings (2016–2024) via the EPA Water Quality Portal. See the full Birch Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 69 ft |
| Average Depth | 26 ft |
| Surface Area | 236 acres |
| Shoreline Length | 6.7 mi |
| Littoral Zone | 30% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Popular LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Birch Lake
DNR Fisheries Survey Summary
8 surveys on file from MN DNR Fisheries. Most recent: 2023-08-21 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Fathead Minnow | 335.62 | — |
| PRD | 9.91 | — |
| IOD | 8.35 | — |
| White Sucker | 3.00 | 1.89 lb |
| Rainbow Trout | 2.32 | 1.47 lb |
| SPT | 2.00 | 0.56 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.
IOD
White Sucker
Rainbow Trout
SPT
From the 2023-08-21 survey
Birch Lake is a 236-acre lake located 34 miles north of Grand Marais and public access is through a carry-in access along the south shore. Rainbow trout are the primary management species with yearlings stocked every year since 2016. Brook trout were last stocked in 2015 and were not captured in the 2023 survey. In…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Birch Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — BirchFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — BirchFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — BirchPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.052 m/yr | 5 |
EPA Impairment Status
Birch Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN16-0245-00 · Official waterbody report · Matched by proximity (2.44 km)
County Ranking
Ranked #2 of 44 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Birch Lake
What is the water quality grade for Birch Lake?
- Birch Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 18 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Maximum depth: 69 ft. Surface area: 236.31 acres.
Is Birch Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Birch Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Birch Lake?
- Birch Lake typically sits around 67°F at the surface in August, from 186 EPA Water Quality Portal field readings (2016–2024). That is a typical value for the month, not a live reading.
How deep is Birch Lake?
- Birch Lake has a maximum depth of 69 feet and an average depth of 26 feet. The lake covers 236.31 acres.
What fish are in Birch Lake?
- Fish species found in Birch Lake include lake trout, rainbow trout, smallmouth bass. Birch Lake is located in Cook County, Minnesota.
Are there boat ramps on Birch Lake?
- Birch Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Popular Lake. Public access is listed as yes.
Explore Birch Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Where this data comes from
39 measurements from 2 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA39 samples · 2020–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
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