Maple Lake
Polk County, Minnesota1,641 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Maple Lake. Here is what has been measured.
- Eutrophic
- 14 ft max depth
- Public access
Maple Lake in Polk County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 38.5 µg/L. Chlorophyll-a (algae): 17.8 µg/L. Maximum depth: 14 ft. Surface area: 1641.02 acres.
Minnesota DNR's Targeted Survey on June 24, 2024 caught 14.22 walleye per gill net at Maple Lake. DNR survey details →
Free interactive depth-contour map of Maple Lake, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Maple Lake is a 1,641-acre productive, nutrient-rich eutrophic lake in Polk County, Minnesota with a maximum depth of 14 feet. Overall water quality is declining over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 2 public boat landings. Compared to the 18 other monitored lakes in Polk County, Maple Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-04. Methodology: how these readings are compared.
Maple Lake covers about 1,600 acres in Polk County. It has 2 public boat landings, so a lakefront rental is not the only way to get a boat on the water. The median ice-out date is April 14, which is when the open-water season begins. Vrbo is where to look for cabins and lake homes around Maple Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Maple Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
- Fishing12 species recorded
- Ice seasonIce-out around Apr 14
- Big water1,641 acres
Swimming conditions
Readings onlyAlgae risk
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. Check local advisories before you swim.
Whether Maple 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 Maple Lake
These are the measurements Minnesota PCA publishes for Maple 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 3.3 ft of visibility. Phosphorus 38.5 µg/L. Chlorophyll-a 17.8 µg/L. TSI 59.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 38.5µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 17.8µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 59 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Maple Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Maple Lake typically sits around 60°F at the surface in September. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in May (about 54°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (54°F) to its warmest (76°F).
Typical surface water temperature by month, from 17 field readings (2011–2021) via the EPA Water Quality Portal. See the full Maple Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Maple Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (570,164 cells/mL) on July 19, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Minnesota DNR's Targeted Survey on June 24, 2024 caught 14.22 walleye per gill net at Maple Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Maple 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
12 surveys on file from MN DNR Fisheries. Most recent: 2024-06-24 (Targeted Survey).
12 surveys on file · most recent 2024-06-24 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 50.77 | 12 in 2021-06-28 | 0.42 lb |
| Spottail Shiner | 33.48 | ||
| Bluegill | 32.36 | 4–9 in 2024-06-24 | 0.26 lb |
| Brown Bullhead | 26.41 | 9–15 in 2024-06-24 | 0.64 lb |
| Largemouth Bass | 15.92 | 15 in 2024-06-24 | 0.85 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.
Black Bullhead
Bluegill
Brown Bullhead
Largemouth Bass
From the 2024-06-24 survey
Maple Lake is a 1,641-acre lake located in northern Polk County, two miles south of Mentor. The maximum depth is 15 feet and the shoreline is considered highly developed with homes and cabins. The lake receives heavy recreational use and angling pressure from the surrounding area. There are two public access points,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Maple Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — MapleFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — MapleFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — MaplePublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
14 ft
Surface area
1,641 acres
Shoreline
19.8 mi
Littoral zone
96%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
29 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,165 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Maple Lake EastPublic
- Maple Lake WestPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Maple Lake
Compare lakeside cabins, hotels, and vacation rentals near Maple Lake in Polk 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 Maple Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Follow Maple Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Maple Lake
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Stable+0.29 µg/L/yr6 years
Chlorophyll-a
Worsening+1.19 µg/L/yr6 years
Ice season
Typical ice-out
Apr 14
Earliest Apr 6, 2017 · Latest Apr 18, 2002
Typical ice-in
Nov 27
Earliest Nov 16, 2003 · Latest Nov 30, 2006
Most recent ice-out
Apr 6
2017
8 observations · Minnesota PCA ice records
Reservoir Info (USACE NID)
Maple Lake is a man-made reservoir impounded by the Maple Lake (completed 1942), built primarily for recreation on the Cyr Creek; gravity-type dam, 8 ft tall and 50 ft long.
- Surface area
- 1,477 ac
- Normal storage
- 11,872 ac-ft
- Max storage
- 20,352 ac-ft
- Drainage area
- 15.1 sq mi
- Hazard class
- Low
- Owner
- County of Polk
Source: USACE National Inventory of Dams, NID ID MN00222 · Operator website
Nearby Lakes in Polk County
Frequently asked questions about Maple Lake
Where is Maple Lake?
- Maple Lake is a lake in Polk County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Maple Lake?
- Maple Lake in Polk County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.3 ft visibility. Phosphorus: 38.5 µg/L. Chlorophyll-a (algae): 17.8 µg/L. Maximum depth: 14 ft. Surface area: 1641.02 acres.
Is Maple Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Maple Lake?
- Maple Lake typically sits around 60°F at the surface in September, from 17 EPA Water Quality Portal field readings (2011–2021). That is a typical value for the month, not a live reading.
How deep is Maple Lake?
- Maple Lake has a maximum depth of 14 feet. The lake covers 1641.02 acres.
What fish are in Maple Lake?
- Fish species found in Maple Lake include black bullhead, black crappie, bluegill, brown bullhead, common carp, freshwater drum, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow perch. Maple Lake is located in Polk County, Minnesota.
What did the DNR fisheries survey find at Maple Lake?
- Minnesota DNR's Targeted Survey on June 24, 2024 caught 14.22 walleye per gill net at Maple Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Maple 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.
When does Maple Lake thaw?
- Maple Lake typically has ice-out around Apr 14. Ice typically forms around Nov 27. The open water season is approximately 227 days.
Does Maple Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Maple Lake (clouds, ice, or an off-season gap). The most recent reading was high (570,164 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Maple Lake?
- Maple Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Maple Lake East, Maple Lake West. Public access is listed as yes.
Can I fish at Maple Lake?
- Maple Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. 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 Maple Lake across LakeQuality
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Fish species and best lakes in Polk County
Species activity outlook by water temperature and season
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Minnesota's cleanest lakes, ranked on agency measurements
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Where this data comes from
271 measurements from 4 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
MNPCA271 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (4)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate