Poplar Lake
Poplar Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.2 ft visibility. Phosphorus: 9 µg/L. Chlorophyll-a (algae): 3.3 µg/L. Maximum depth: 30 ft. Surface area: 23.2 acres.
- Clarity
- 10.2 ft
- Typical in August
- 57°F
- Max depth
- 30 ft
- Area
- 23 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- No
Next lake in Cook County
Poplar Lake is a 23-acre mesotrophic lake in Cook County, Minnesota with a maximum depth of 30 feet (8-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 3 documented fish species including brook trout, northern pike, and white sucker. No public access — the lake is private or restricted. Compared to the 43 other monitored lakes in Cook County, Poplar Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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)
Good clarity, visible to about 10.2 ft. Phosphorus level: 9 µg/L. Chlorophyll-a: 3.3 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.2 ft | Not graded |
| Phosphorus | 9 µg/L | Good |
| Chlorophyll-a (Algae) | 3.3 µg/L | Good |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Poplar Lake
Compare lakeside cabins, hotels, and vacation rentals near Poplar 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
Poplar Lake typically sits around 57°F at the surface in August. Summer average is about 58°F. Usually warmest in Jul (about 59°F) and coldest in May (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 175 field readings (2010–2025) via the EPA Water Quality Portal. See the full Poplar Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 30 ft |
| Average Depth | 8.3 ft |
| Surface Area | 23 acres |
| Shoreline Length | 1.5 mi |
| Littoral Zone | 91% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Poplar Lake
DNR Fisheries Survey Summary
5 surveys on file from MN DNR Fisheries. Most recent: 2013-10-03 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Brook Trout | 11.54 | 1.48 lb |
| Pumpkinseed | 6.22 | 0.07 lb |
| Yellow Perch | 5.58 | 0.14 lb |
| White Sucker | 3.71 | 1.15 lb |
| Northern Pike | 3.17 | 2.07 lb |
| Walleye | 1.00 | 4.25 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.
Brook Trout
Pumpkinseed
Yellow Perch
White Sucker
From the 2013-10-03 survey
In June 2013 a local guide reported seeing northern pike in Lizz Lake, and he reported there were no more brook trout present. This assessment was done to confirm that report. Lizz Lake was reclaimed for stream trout management in 1985, using a fish toxicant to remove its original fish community (walleye, northern…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Poplar Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LizzFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.168 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.2 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.16 µg/L/yr | 6 |
EPA Impairment Status
Poplar 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 MN16-0239-00 · Official waterbody report
County Ranking
Ranked #11 of 44 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Poplar Lake
What is the water quality grade for Poplar Lake?
- Poplar Lake in Cook County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.2 ft visibility. Phosphorus: 9 µg/L. Chlorophyll-a (algae): 3.3 µg/L. Maximum depth: 30 ft. Surface area: 23.2 acres.
Is Poplar Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Poplar Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 3.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Poplar Lake?
- Poplar Lake typically sits around 57°F at the surface in August, from 175 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Poplar Lake?
- Poplar Lake has a maximum depth of 30 feet and an average depth of 8.3 feet. The lake covers 23.2 acres.
What fish are in Poplar Lake?
- Fish species found in Poplar Lake include brook trout, northern pike, white sucker. Poplar Lake is located in Cook County, Minnesota.
Explore Poplar Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
77 measurements from 3 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA77 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (3)
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