Little Rock Lake
Benton County, Minnesota1,311 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Little Rock Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Mercury
- zebra mussel
- 17 ft max depth
- Public access
Little Rock Lake in Benton County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 156.5 µg/L. Chlorophyll-a (algae): 115 µg/L. Maximum depth: 17 ft. Surface area: 1310.66 acres.
Minnesota DNR's Standard Survey on June 18, 2025 caught 1.45 walleye per gill net at Little Rock Lake. Length samples in the latest survey that recorded them ran 4–24 inches. DNR survey details →
Free interactive depth-contour map of Little Rock Lake, reaching a maximum surveyed depth of 15 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Little Rock Lake is a 1,311-acre highly nutrient-loaded hypereutrophic lake in Benton County, Minnesota with a maximum depth of 17 feet (8-foot average). Overall water quality is declining over recent sampling years. The lake supports 21 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 2025-09-17. Methodology: how these readings are compared.
What Little Rock Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing21 species recorded
- Ice seasonIce-out around Apr 10
- Big water1,311 acres
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Little Rock Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Little Rock Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Little Rock Lake
These are the measurements Minnesota PCA publishes for Little Rock Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.8 ft of visibility. Phosphorus 156.5 µg/L. Chlorophyll-a 115 µg/L. TSI 74.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 157µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 115µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 74 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Little Rock Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Little Rock Lake typically sits around 58°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 74°F) and coldest in Sep (about 58°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (58°F) to its warmest (74°F).
Typical surface water temperature by month, from 21 field readings (2016–2016) via the EPA Water Quality Portal. See the full Little Rock Lake water temperature breakdown →
Minnesota DNR's Standard Survey on June 18, 2025 caught 1.45 walleye per gill net at Little Rock Lake. Length samples in the latest survey that recorded them ran 4–24 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Little Rock Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
27 surveys on file from MN DNR Fisheries. Most recent: 2025-06-18 (Standard Survey).
27 surveys on file · most recent 2025-06-18 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Perch | 28.03 | 4–5 in 2025-06-18 | 0.18 lb |
| Walleye | 24.35 | 4–24 in 2025-06-18 | 1.07 lb |
| Black Bullhead | 17.86 | 14 in 2020-07-13 | 0.6 lb |
| Black Crappie | 12.57 | 5–6 in 2025-06-18 | 0.28 lb |
| Bigmouth Buffalo | 10.83 | 10–14 in 2025-06-18 | 6.59 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
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.
Yellow Perch
Walleye
Black Bullhead
Black Crappie
From the 2025-06-18 survey
Little Rock Lake (DOW# 05-0013-00; Lake Class 41) is a 1,450-acre reservoir located near Rice, Minnesota. A Minnesota Department of Natural Resources (MNDNR) owned concrete boat ramp is located rear State Highway 10 near the south end of the lake. Little Rock Lake has 10.55 miles of shoreline and a maximum depth of 17…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Little Rock Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Little RockFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Little Rock (1980)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — Little RockPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
17 ft
Average depth
8 ft
Surface area
1,311 acres
Shoreline
10.6 mi
Littoral zone
95%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
118 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,007 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Benton BeachPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Little Rock Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Rock Lake in Benton 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Little Rock Lake are listed below.
Top-rated places to stay near Little Rock Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 →
Follow Little Rock Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Little Rock Lake
- → Little Rock Lake fishing: DNR survey catch rates, species & stocking
- → Little Rock Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Little Rock Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Little Rock Lake? (mercury & PFAS guide)
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Worsening+7.93 µg/L/yr6 years
Chlorophyll-a
Worsening+11.18 µg/L/yr6 years
Ice season
Typical ice-out
Apr 10
Earliest Mar 9, 2024 · Latest May 2, 2018
Typical ice-in
Nov 25
Earliest Nov 3, 1991 · Latest Dec 31, 2023
Most recent ice-out
Mar 28
2025
94 observations · Minnesota PCA ice records
EPA Impairment Status
Little Rock Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN05-0013-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Little Rock Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Rice WwtpRice · 2.9 mi away · NPDES MN0056481Recent 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.
Nearby Lakes in Benton County
Frequently asked questions about Little Rock Lake
Where is Little Rock Lake?
- Little Rock Lake is a lake in Benton County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Little Rock Lake?
- Little Rock Lake in Benton County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.8 ft visibility. Phosphorus: 156.5 µg/L. Chlorophyll-a (algae): 115 µg/L. Maximum depth: 17 ft. Surface area: 1310.66 acres.
Is Little Rock Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Little Rock Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Little Rock Lake?
- Little Rock Lake typically sits around 58°F at the surface in September, from 21 EPA Water Quality Portal field readings (2016–2016). That is a typical value for the month, not a live reading.
How deep is Little Rock Lake?
- Little Rock Lake has a maximum depth of 17 feet and an average depth of 8 feet. The lake covers 1310.66 acres.
What fish are in Little Rock Lake?
- Fish species found in Little Rock Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, channel catfish, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, shorthead redhorse, silver redhorse, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Little Rock Lake is located in Benton County, Minnesota.
What did the DNR fisheries survey find at Little Rock Lake?
- Minnesota DNR's Standard Survey on June 18, 2025 caught 1.45 walleye per gill net at Little Rock Lake. Length samples in the latest survey that recorded them ran 4–24 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Little Rock Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Little Rock Lake thaw?
- Little Rock Lake typically has ice-out around Apr 10. Ice typically forms around Nov 25. The open water season is approximately 229 days.
Are there boat ramps on Little Rock Lake?
- Little Rock Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Benton Beach. Public access is listed as yes.
Can I fish at Little Rock Lake?
- Little Rock Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Little Rock Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Minnesota
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Minnesota's cleanest lakes, ranked on agency measurements
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State Parks Near Little Rock Lake
Other Lakes in Minnesota
Hypereutrophic Lakes in Minnesota
Where this data comes from
274 measurements from 3 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 Water
MNPCA274 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (3)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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