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LakeQuality

String Lake

NR
Not yet rated
0.3 ft clear · Hypereutrophic · 336 acres
Limited DataHypereutrophic

String Lake in Cottonwood County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.3 ft visibility. Maximum depth: 3.8 ft. Surface area: 336.23 acres.

Clarity
0.3 ft
Max depth
3.8 ft
Area
336 acres
Public access
Yes

Next lake in Cottonwood County

DCottonwood Lake2.1 ft clear · Cottonwood CountyView →
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Why String Lake has no grade

We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For String Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).

Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.

Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.

String Lake is a 336-acre lake in Cottonwood County, Minnesota with a maximum depth of 4 feet. The lake supports 11 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-07-18. Grade methodology: LakeGrade methodology.

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Swimming Safety

Not rated

Limited data

Not rated for swimming — there is not enough monitoring data to judge this lake

Compare the safest swimming lakes near Mankato

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Water quality measurements for String Lake

These readings exist but do not meet the evidence bar for an A–F grade — see why.

Very murky, less than 0.3 ft of visibility. Trophic State Index: 93.

MetricValueGrade
Water Clarity (Secchi Depth)0.3 ftNot graded
PhosphorusNo recent samples
Chlorophyll-a (Algae)No recent samples
Trophic State Index (TSI)93Hypereutrophic

Very high nutrients, dense algae, poor clarity

Where to stay near String Lake

Compare lakeside cabins, hotels, and vacation rentals near String Lake in Cottonwood 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 String 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 Depth3.8 ft
Surface Area336 acres
Shoreline Length7 mi
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
9 sq mi
Elevation
1,401 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).

Recreation & Access

1
Boat Landings
Yes
Public Access
  • String LakePublic

Fish Species

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

Fishing String Lake

DNR Fisheries Survey Summary

2 surveys on file from MN DNR Fisheries. Most recent: 2023-05-15 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Fathead Minnow53.03
Bigmouth Buffalo41.135.55 lb
Black Bullhead17.500.36 lb
Yellow Perch8.840.09 lb
Black Crappie5.380.13 lb
Common Carp5.055.06 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.

Bigmouth Buffalo

14 fish · 1128 in · 2016-06-08
320121416182022242628

Black Bullhead

7 fish · 89 in · 2023-05-15
53089

Yellow Perch

2 fish · 33 in · 2023-05-15
2103

Black Crappie

43 fish · 410 in · 2016-06-08
22110trophy 1045678910

From the 2023-05-15 survey

String Lake is a 402-acre, class 42 lake located four miles west of the City of Windom in Cottonwood County. String Lake is comprised of three basins divided by roads but are connected by culverts that allow fish passage. String Lake is a shallow basin (max depth of 6.0 ft.) that experiences frequent partial…

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 String Lake. 3 reports on file.

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

Regulated Pollution Sources Nearby

1 EPA-permitted facility operate within about 5 miles of String Lake under Clean Water Act (NPDES) discharge permits.

  • Red Rock Rural Wtp
    Windom · 3.3 mi away · NPDES MN0068101

Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.

Graded lakes near String Lake

String Lake has no grade, but these lakes within a short drive do.

Nearby Lakes in Cottonwood County

Frequently asked questions about String Lake

What is the water quality grade for String Lake?

String Lake in Cottonwood County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.3 ft visibility. Maximum depth: 3.8 ft. Surface area: 336.23 acres.

Is String Lake safe to swim in?

Not rated for swimming — there is not enough monitoring data to judge this lake. String Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.

How deep is String Lake?

String Lake has a maximum depth of 3.8 feet. The lake covers 336.23 acres.

What fish are in String Lake?

Fish species found in String Lake include bigmouth buffalo, black bullhead, black crappie, channel catfish, common carp, green sunfish, northern pike, orangespotted sunfish, walleye, white sucker, yellow perch. String Lake is located in Cottonwood County, Minnesota.

Are there boat ramps on String Lake?

String Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include String Lake. Public access is listed as yes.

Where this data comes from

1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Minnesota Department of Agriculture - Pesticide MonitoringMNDA_PESTICIDE1 sample · 2022

Analytical methods

  • Field measurement/observation, generic method
Monitoring station identifiers (1)

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

Regulated discharger data from EPA ECHO (ICIS-NPDES)

Lake size & watershed from HydroLAKES (HydroSHEDS)

Lake details from Minnesota DNR LakeFinder

Named boat-access points from the USGS National Boat Ramps inventory