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LakeQuality

Roberds Lake

F
Grade F — Algae-prone
Algae-prone · #4 of 14 lakes in the county · 2.5 ft clear · Hypereutrophic · 632 acres
Limited DataHypereutrophic

Roberds Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 300 µg/L. Chlorophyll-a (algae): 86.7 µg/L. Maximum depth: 43 ft. Surface area: 632.29 acres.

Clarity
2.5 ft
Typical in August
74°F
Max depth
43 ft
Area
632 acres
Type
Hypereutrophic
Trend
Stable
Public access
Yes
Ice-out
Apr 3
Open water
242 days

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

Next lake in Rice County

DDudley Lake9 ft clear · Rice CountyView →
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Roberds Lake is a 632-acre highly nutrient-loaded hypereutrophic lake in Rice County, Minnesota with a maximum depth of 43 feet. Water quality is graded F based on 2 sampling years through 2025. The lake supports 18 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 13 other monitored lakes in Rice County, Roberds Lake ranks #4 for water quality.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-08. Grade methodology: LakeGrade methodology.

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Swimming Safety

Grade only

Limited data

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.

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom

Compare the safest swimming lakes near Mankato

Get alerts for Roberds Lake

Water Quality Grade: F (Algae-prone)

Very murky, less than 2.5 ft of visibility. Phosphorus level: 300 µg/L. Chlorophyll-a: 86.7 µg/L. Trophic State Index: 75.

MetricValueGrade
Water Clarity (Secchi Depth)2.5 ftNot graded
Phosphorus300 µg/LPoor
Chlorophyll-a (Algae)86.7 µg/LPoor
Trophic State Index (TSI)75Hypereutrophic

Very high nutrients, dense algae, poor clarity

Where to stay near Roberds Lake

Compare lakeside cabins, hotels, and vacation rentals near Roberds Lake in Rice 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 Roberds Lake are listed below.

Top-rated places to stay near Roberds 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

Roberds Lake typically sits around 74°F at the surface in August. Summer average is about 71°F. Usually warmest in Sep (about 75°F) and coldest in May (about 51°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
51°
Jun
66°
Jul
73°
Aug
74°
Sep
75°
Oct
63°
Nov
Dec

Typical surface water temperature by month, from 89 field readings (20162025) via the EPA Water Quality Portal. See the full Roberds Lake water temperature breakdown →

Blue-Green Algae (Cyanobacteria)

No current satellite reading

There’s no recent EPA CyAN cyanobacteria estimate for Roberds Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (731,139 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 ↗

Lake Details

CharacteristicValue
Maximum Depth43 ft
Surface Area632 acres
Shoreline Length5.6 mi
Littoral Zone62%
Public AccessYes

Lake Size & Watershed

Watershed (drainage) area
15 sq mi
Elevation
1,017 ft

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

Recreation & Access

1
Boat Landings
Yes
Public Access
  • Roberds LakePublic

Fish Species

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

Fishing Roberds Lake

DNR Fisheries Survey Summary

14 surveys on file from MN DNR Fisheries. Most recent: 2023-10-23 (Targeted Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Largemouth Bass3856.081.21 lb
Black Bullhead32.070.78 lb
Black Crappie23.730.32 lb
Bluegill13.270.29 lb
Yellow Perch12.830.2 lb
Freshwater Drum6.961.97 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.

Largemouth Bass

54 fish · 618 in · 2023-06-26
14706789101112131415161718

Black Bullhead

60 fish · 914 in · 2023-06-26
2412091011121314

Black Crappie

92 fish · 314 in · 2023-06-26
31160trophy 1034567891011121314

Bluegill

108 fish · 310 in · 2023-06-26
43220trophy 10345678910

From the 2023-10-23 survey

A survey targeting age-0 Walleye was conducted at Roberds Lake on 23 October 2023 using 56 minutes of standard boat electrofishing. Zero age-0 Walleye were sampled for a catch rate of 0.0/hour on-time. Catch rates have averaged 3.1/hour on-time during 7 surveys since 2017. During that period non-stocked years (n = 4)…

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 Roberds 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 Stable-0.015 m/yr6
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (65 observations).

Typical Ice-Out
Apr 3
Typical Ice-In
Dec 1

Estimated open water season: 242 days

EarliestLatest
Ice-Out2024-02-29 (2024)2018-04-30 (2018)
Ice-In1995-11-09 (1995)2001-12-21 (2001)

Most recent ice-out: 2026-03-26

EPA Impairment Status

Roberds 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 MN66-0018-00 · Official waterbody report

County Ranking

Ranked #4 of 14 lakes in Rice County

Nearby Lakes With Higher Grades

Roberds Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.

Nearby Lakes in Rice County

DDudley Lake9 ft clear · EutrophicView →CKelly Lake8.2 ft clear · EutrophicView →
FWells Lake2 ft clear · HypereutrophicCompareView →
FFrench Lake1.7 ft clear · HypereutrophicCompareView →
FCannon Lake4.1 ft clear · EutrophicCompareView →
FMazaska Lake2.5 ft clear · EutrophicCompareView →

Frequently asked questions about Roberds Lake

What is the water quality grade for Roberds Lake?

Roberds Lake in Rice County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2.5 ft visibility. Phosphorus: 300 µg/L. Chlorophyll-a (algae): 86.7 µg/L. Maximum depth: 43 ft. Surface area: 632.29 acres.

Is Roberds Lake safe to swim in?

Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Roberds Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 86.7 µg/L. Always check local health department advisories before swimming.

What is the water temperature of Roberds Lake?

Roberds Lake typically sits around 74°F at the surface in August, from 89 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.

How deep is Roberds Lake?

Roberds Lake has a maximum depth of 43 feet. The lake covers 632.29 acres.

What fish are in Roberds Lake?

Fish species found in Roberds Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, channel catfish, common carp, crappie, freshwater drum, largemouth bass, muskellunge, northern pike, walleye, white bass, white crappie, yellow bullhead, yellow perch. Roberds Lake is located in Rice County, Minnesota.

When does Roberds Lake thaw?

Roberds Lake typically has ice-out around Apr 3. Ice typically forms around Dec 1. The open water season is approximately 242 days.

Does Roberds Lake have blue-green algae?

There is no recent EPA CyAN cyanobacteria estimate for Roberds Lake (clouds, ice, or an off-season gap). The most recent reading was high (731,139 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.

Are there boat ramps on Roberds Lake?

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

Hypereutrophic Lakes in Minnesota

Where this data comes from

72 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 WaterMNPCA72 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

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