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LakeQuality

Rays Lake

NR
Not yet rated
3.5 ft clear · Eutrophic · 169 acres
Limited DataEutrophic

Rays Lake in Le Sueur County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.5 ft visibility. Maximum depth: 32 ft. Surface area: 168.93 acres.

Clarity
3.5 ft
Typical in August
69°F
Max depth
32 ft
Area
169 acres
Trend
Improving
Public access
Yes
Ice-out
Mar 29
Open water
252 days

Next lake in Le Sueur County

CFish Lake11.8 ft clear · Le Sueur CountyView →
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Why Rays 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 Rays Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. 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.

Rays Lake is a 169-acre lake in Le Sueur County, Minnesota with a maximum depth of 32 feet. Overall water quality is improving over recent sampling years. The lake supports 15 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 4 public boat landings.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-31. 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

Get alerts for Rays Lake

Water quality measurements for Rays Lake

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

Murky, only visible to about 3.5 ft. Trophic State Index: 59.

MetricValueGrade
Water Clarity (Secchi Depth)3.5 ftNot graded
PhosphorusNo recent samples
Chlorophyll-a (Algae)No recent samples
Trophic State Index (TSI)59Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Rays Lake

Compare lakeside cabins, hotels, and vacation rentals near Rays Lake in Le Sueur 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 Rays 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

Rays Lake typically sits around 69°F at the surface in August. Summer average is about 68°F. Usually warmest in Jul (about 69°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
61°
Jun
66°
Jul
69°
Aug
69°
Sep
68°
Oct
Nov
Dec

Typical surface water temperature by month, from 245 field readings (20172025) via the EPA Water Quality Portal. See the full Rays Lake water temperature breakdown →

Lake Details

CharacteristicValue
Maximum Depth32 ft
Surface Area169 acres
Shoreline Length2.2 mi
Littoral Zone82%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
9 sq mi
Elevation
1,014 ft

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

Recreation & Access

4
Boat Landings
Yes
Public Access
  • Lily LakePublic
  • Rays LakePublic
  • Lake FrancesPublic
  • Elysian LakePublic

Fish Species

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

Fishing Rays 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 watermilfoil

DNR Fisheries Survey Summary

10 surveys on file from MN DNR Fisheries. Most recent: 2021-07-26 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Black Bullhead34.250.47 lb
Bluegill32.640.13 lb
Bluntnose Minnow23.99
Green Sunfish23.83
Black Crappie15.930.2 lb
Yellow Bass3.060.83 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

16 fish · 912 in · 2020-07-10
9509101112

Bluegill

267 fish · 38 in · 2021-07-26
90450345678

Bluntnose Minnow

1 fish · 00 in · 2003-07-21
100

Green Sunfish

3 fish · 24 in · 2003-07-21
210234

From the 2021-07-26 survey

Rays (Charles) Lake is a 156.3-acre lake located in Le Sueur County north of the town of Elysian. A public access is located on the south side of the lake off 1st Street North, which goes north from Elysian. Rays Lake has a maximum depth of 32.0 feet. Eurasian watermilfoil is present in Rays Lake. Boaters should be…

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 Rays Lake. 2 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 Stable-0.009 m/yr6
Phosphorus Improving-4 µg/L/yr2
Chlorophyll-a Improving-4.7 µg/L/yr2
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (12 observations).

Typical Ice-Out
Mar 29
Typical Ice-In
Dec 6

Estimated open water season: 252 days

EarliestLatest
Ice-Out2015-03-21 (2015)2008-04-16 (2008)
Ice-In2008-11-19 (2008)2004-12-14 (2004)

Most recent ice-out: 2015-03-21

EPA Impairment Status

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

Causes of impairment

Nutrients (phosphorus, nitrogen)

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

Source: EPA ATTAINS assessment unit MN40-0061-00 · Official waterbody report · Matched by proximity (0.9 km)

Regulated Pollution Sources Nearby

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

  • Elysian
    Elysian · 0.5 mi away · NPDES MN0041114

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 Rays Lake

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

Nearby Lakes in Le Sueur County

Frequently asked questions about Rays Lake

What is the water quality grade for Rays Lake?

Rays Lake in Le Sueur County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.5 ft visibility. Maximum depth: 32 ft. Surface area: 168.93 acres.

Is Rays Lake safe to swim in?

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

What is the water temperature of Rays Lake?

Rays Lake typically sits around 69°F at the surface in August, from 245 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.

How deep is Rays Lake?

Rays Lake has a maximum depth of 32 feet. The lake covers 168.93 acres.

What fish are in Rays Lake?

Fish species found in Rays Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, freshwater drum, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead, yellow perch. Rays Lake is located in Le Sueur County, Minnesota.

When does Rays Lake thaw?

Rays Lake typically has ice-out around Mar 29. Ice typically forms around Dec 6. The open water season is approximately 252 days.

Are there boat ramps on Rays Lake?

Rays Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lily Lake, Rays Lake, Lake Frances, Elysian Lake. Public access is listed as yes.

Where this data comes from

34 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • Minnesota Pollution Control Agency - Ambient Surface WaterMNPCA34 samples · 2020–2025

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

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