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LakeQuality

Unnamed Lake

D
Grade D — Nutrient-rich
Nutrient-rich · #48 of 75 lakes in the county · 3 ft clear · Eutrophic · 1,799 acres
Eutrophic

Unnamed Lake in Washington County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3 ft visibility. Phosphorus: 77 µg/L. Chlorophyll-a (algae): 28.5 µg/L. Maximum depth: 60 ft. Surface area: 1799.22 acres.

Clarity
3 ft
Max depth
60 ft
Area
1,799 acres
Type
Eutrophic
Public access
Yes
Ice-out
Apr 8
Open water
241 days

Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Unnamed Lake →

Find a place to stay →Safe to swim?

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Unnamed Lake is a 1,799-acre productive, nutrient-rich eutrophic lake in Washington County, Minnesota with a maximum depth of 60 feet. Water quality is graded D based on 2 sampling years through 2025. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available. Compared to the 74 other monitored lakes in Washington County, Unnamed Lake ranks #48 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-24. Grade methodology: LakeGrade methodology.

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Swimming Safety

Grade only

Algae risk

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.

Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum

Compare the safest swimming lakes near St. Paul →

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Water Quality Grade: D (Nutrient-rich)

Very murky, less than 3 ft of visibility. Phosphorus level: 77 µg/L. Chlorophyll-a: 28.5 µg/L. Trophic State Index: 64.

MetricValueGrade
Water Clarity (Secchi Depth)3 ftNot graded
Phosphorus77 µg/LPoor
Chlorophyll-a (Algae)28.5 µg/LPoor
Trophic State Index (TSI)64Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Unnamed Lake

Compare lakeside cabins, hotels, and vacation rentals near Unnamed Lake in Washington 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 grade measures nutrients and algae, not lodging — cabins and rentals around Unnamed Lake are listed below.

Top-rated places to stay near Unnamed Lake

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 →

Lake Details

CharacteristicValue
Maximum Depth60 ft
Surface Area1,799 acres
Shoreline Length16.8 mi
Littoral Zone64%
Public AccessYes

Fish Species

black bullheadblack crappiebluegillbrown bullheadgreen sunfishhybrid sunfishlargemouth bassnorthern pikepumpkinseedwalleyeyellow bullheadyellow perch

Click a species to see every graded lake where it is documented.

Fishing Unnamed 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.

Eurasian watermilfoilzebra mussel

DNR Fisheries Survey Summary

23 surveys on file from MN DNR Fisheries. Most recent: 2024-07-29 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluntnose Minnow37.28—
Bluegill35.710.15 lb
BCS18.41—
GOS12.060.07 lb
BLH11.600.61 lb
BNS11.51—

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

83 fish · 4–8 in · 2024-07-29
3819045678

GOS

1 fish · 5–5 in · 2024-07-29
105

From the 2024-07-29 survey

Big Marine Lake is a 1,799 acre, class 24 lake located in northern Washington County. Big Marine Lake is mesotrophic, moderately fertile, and is primarily managed for Walleye and Largemouth Bass. Bluegill and Black Crappie are secondary management species. From 1995 to 2017, Big Marine Lake was stocked with Walleye…

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 Unnamed Lake. 3 reports on file.

These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).

Ice Season

Historical ice data from Minnesota DNR (8 observations).

Typical Ice-Out
Apr 8
Typical Ice-In
Dec 5

Estimated open water season: 241 days

EarliestLatest
Ice-Out2026-03-31 (2026)2014-04-25 (2014)
Ice-In2005-11-28 (2005)2004-12-14 (2004)

Most recent ice-out: 2026-03-31

County Ranking

Ranked #48 of 75 lakes in Washington County

Nearby Lakes in Washington County

DSunnybrook Lake4.5 ft clear · EutrophicView →FKlawitter Pond1.9 ft clear · EutrophicView →CLong Lake8 ft clear · MesotrophicView →AWood Pile Lake10 ft clear · MesotrophicView →AJane Lake13 ft clear · MesotrophicView →AMaster Man Lake4.5 ft clear · MesotrophicView →

Frequently asked questions about Unnamed Lake

What is the water quality grade for Unnamed Lake?

Unnamed Lake in Washington County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 3 ft visibility. Phosphorus: 77 µg/L. Chlorophyll-a (algae): 28.5 µg/L. Maximum depth: 60 ft. Surface area: 1799.22 acres.

Is Unnamed Lake safe to swim in?

Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Unnamed Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 28.5 µg/L. Always check local health department advisories before swimming.

How deep is Unnamed Lake?

Unnamed Lake has a maximum depth of 60 feet. The lake covers 1799.22 acres.

What fish are in Unnamed Lake?

Fish species found in Unnamed Lake include black bullhead, black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. Unnamed Lake is located in Washington County, Minnesota.

When does Unnamed Lake thaw?

Unnamed Lake typically has ice-out around Apr 8. Ice typically forms around Dec 5. The open water season is approximately 241 days.

Explore Unnamed Lake across LakeGrade

Minnesota Fishing Guide

Fish species and top-graded lakes across Minnesota

Washington County Fishing

Fish species and best lakes in Washington County

Lake Fishing Forecast

Species activity outlook by water temperature and season

Minnesota Lake Trips

Where to stay at Minnesota's top lakes, each with its grade

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Grade A/B + low algae filter

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State Parks Near Unnamed Lake

Afton State Park

State Park · 13.9 mi

William O'Brien State Park

State Park · 13.9 mi

Fort Snelling State Park

State Park · 17.2 mi

Other Grade D Lakes in Minnesota

Silver Lake

Ramsey County · 7 ft

Beaver Lake

Ramsey County · 7.7 ft

Bald Eagle Lake

Ramsey County · 5.6 ft

Wakefield Lake

Ramsey County · 5.9 ft

Kohlman Lake

Ramsey County · 3.6 ft

Keller Lake

Ramsey County · 4.3 ft

Eutrophic Lakes in Minnesota

Silver LakeBeaver LakeBald Eagle LakeGem Lake

Compare Unnamed Lake With Nearby Lakes

Unnamed Lake vs White Bear Lake

Washington County · Grade A

Where this data comes from

858 measurements from 19 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 WaterMNPCA857 samples · 2020–2025
  • Minnesota Department of Agriculture - Pesticide MonitoringMNDA_PESTICIDE1 sample · 2022

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by Two Reagent Colorimetry
  • 10200 H ~ Chlorophyll a-b-c Determination
  • Phosphorus by Colorimetry
  • Analysis of Chlorophyll in Periphyton and Plankton
  • Turbidity, Nephelometric Method
  • 2120 B ~ Color in Water by Visual Comparison
Monitoring station identifiers (19)

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

Lake details from Minnesota DNR LakeFinder

Ice data from Minnesota DNR Climate