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St James Lake

C
Grade C — Fair
Fair · #1 of 4 lakes in the county · 3 ft clear · Eutrophic · 203 acres · from D
Eutrophic

St James Lake in Watonwan County, Minnesota has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 51.5 µg/L. Chlorophyll-a (algae): 16.3 µg/L. Maximum depth: 15.4 ft. Surface area: 202.76 acres.

Clarity
3 ft
Typical in August
78°F
Max depth
15.4 ft
Area
203 acres
Type
Eutrophic
Trend
Declining
Public access
Yes
Ice-out
Apr 7
Open water
258 days

Next lake in Watonwan County

DLong Lake2.5 ft clear · Watonwan CountyView →
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St James Lake is a 203-acre productive, nutrient-rich eutrophic lake in Watonwan County, Minnesota with a maximum depth of 15 feet. Water quality is graded C based on 2 sampling years through 2025. 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 1 public boat landing. Compared to the 3 other monitored lakes in Watonwan County, St James Lake ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-21. 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.

Swim with caution, moderate algae may be present

Compare the safest swimming lakes near Mankato

Get alerts for St James Lake

Water Quality Grade: C (Fair)

Very murky, less than 3 ft of visibility. Phosphorus level: 51.5 µg/L. Chlorophyll-a: 16.3 µg/L. Trophic State Index: 60.

MetricValueGrade
Water Clarity (Secchi Depth)3 ftNot graded
Phosphorus51.5 µg/LFair
Chlorophyll-a (Algae)16.3 µg/LFair
Trophic State Index (TSI)60Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near St James Lake

Compare lakeside cabins, hotels, and vacation rentals near St James Lake in Watonwan 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 St James 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 →

Water Temperature

St James Lake typically sits around 78°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 78°F) and coldest in Apr (about 45°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
45°
May
60°
Jun
75°
Jul
78°
Aug
78°
Sep
71°
Oct
56°
Nov
Dec

Typical surface water temperature by month, from 189 field readings (20102025) via the EPA Water Quality Portal. See the full St James Lake water temperature breakdown →

Lake Details

CharacteristicValue
Maximum Depth15.4 ft
Surface Area203 acres
Shoreline Length3.7 mi
Littoral Zone100%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
3 sq mi
Elevation
1,070 ft

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

Recreation & Access

1
Boat Landings
Yes
Public Access
  • St. James LakePublic

Fish Species

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

Fishing St James Lake

DNR Fisheries Survey Summary

15 surveys on file from MN DNR Fisheries. Most recent: 2025-06-03 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Bullhead41.390.51 lb
Bluegill26.350.21 lb
Yellow Perch19.180.19 lb
Largemouth Bass18.031.45 lb
Common Carp10.302.4 lb
Green Sunfish7.380.29 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.

Black Bullhead

11 fish · 712 in · 2025-06-03
740789101112

Bluegill

80 fish · 48 in · 2025-06-03
3618045678

Yellow Perch

11 fish · 49 in · 2025-06-03
740456789

Largemouth Bass

28 fish · 321 in · 2025-06-03
740trophy 20468101214161820

From the 2025-06-03 survey

St. James Lake is a 252-acre, class 42 lake located in the City of St. James in Watonwan County. The Lake has a maximum depth of 15.4 ft. Winterkills in the mid-1990's suppressed gamefish populations, allowing rough fish to thrive, eventually changing the lake from a clear water state to a turbid state. In 2001, a…

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 St James Lake. 3 reports on file.

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

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.111 m/yr6
Phosphorus Declining+3.43 µg/L/yr4
Chlorophyll-a Stable+0.29 µg/L/yr4
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (16 observations).

Typical Ice-Out
Apr 7
Typical Ice-In
Dec 21

Estimated open water season: 258 days

EarliestLatest
Ice-Out2012-03-13 (2012)2018-04-29 (2018)
Ice-In2007-11-14 (2007)2020-12-29 (2020)

Most recent ice-out: 2022-04-05

EPA Impairment Status

St James Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN83-0043-00 · Official waterbody report

Regulated Pollution Sources Nearby

1 EPA-permitted facility operate within about 5 miles of St James Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.

  • Saint James Wwtp
    Saint James · 1.7 mi away · NPDES MN0024759
    MajorRecent violation

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.

County Ranking

Ranked #1 of 4 lakes in Watonwan County

Nearby Lakes in Watonwan County

Frequently asked questions about St James Lake

What is the water quality grade for St James Lake?

St James Lake in Watonwan County, Minnesota has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 51.5 µg/L. Chlorophyll-a (algae): 16.3 µg/L. Maximum depth: 15.4 ft. Surface area: 202.76 acres.

Is St James Lake safe to swim in?

Swim with caution, moderate algae may be present. St James Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 16.3 µg/L. Always check local health department advisories before swimming.

What is the water temperature of St James Lake?

St James Lake typically sits around 78°F at the surface in August, from 189 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.

How deep is St James Lake?

St James Lake has a maximum depth of 15.4 feet. The lake covers 202.76 acres.

What fish are in St James Lake?

Fish species found in St James Lake include black bullhead, black crappie, bluegill, channel catfish, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow perch. St James Lake is located in Watonwan County, Minnesota.

When does St James Lake thaw?

St James Lake typically has ice-out around Apr 7. Ice typically forms around Dec 21. The open water season is approximately 258 days.

Are there boat ramps on St James Lake?

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

State Parks Near St James Lake

Where this data comes from

147 measurements from 2 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 WaterMNPCA147 samples · 2020–2025

Analytical methods

  • Field measurement/observation, generic method
  • Phosphorus by 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

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

Ice data from Minnesota DNR Climate