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B

Grand Lake

Stearns County, MinnesotaMesotrophic

Grand Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

Mesotrophic conditions dominate at Grand Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. A maximum depth of 34 ft puts Grand Lake in the middle of Minnesota's depth distribution. The lake's 651 acres and 3.8 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Grand Lake ranks 25 of 55 in Stearns County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Grand Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Grand Lake, one of 14 fish species on record for the lake. A documented public access point at Grand Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 12 times at Grand Lake, with a median around Apr 19. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-08-25. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 8 ft. Phosphorus level: 27 µg/L. Trophic State Index: 49.

MetricValueGrade
Water Clarity (Secchi Depth)8 ftC
Phosphorus27 µg/LB
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)49Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth34 ft
Average Depth19 ft
Surface Area650.53 acres
Shoreline Length3.8 mi
Littoral Zone36%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,bowfin (dogfish),brown bullhead,green sunfish,hybrid sunfish,largemouth bass,northern pike,pumpkinseed,walleye,white sucker,yellow bullhead,yellow perch

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Grand Lake (14-day solunar calendar)

→ Is it safe to eat fish from Grand Lake? (mercury & PFAS guide)

Grand Lake fishing regulations (limits, seasons, special rules)

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

starry stonewortzebra mussel

Water Quality Trend: Declining

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.076 m/yr5
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (23 observations).

Typical Ice-Out
Apr 19
Typical Ice-In
Nov 28

Estimated open water season: 223 days

EarliestLatest
Ice-Out1996-02-24 (1996)2014-04-27 (2014)
Ice-In1996-11-13 (1996)2001-12-21 (2001)

Most recent ice-out: 2014-04-27

Location

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County Ranking

Ranked #25 of 55 lakes in Stearns County

Nearby Lakes in Stearns County

DNR Fisheries Survey Summary

10 surveys on file from MN DNR Fisheries. Most recent: 2025-08-18 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
BKF91.20
Bluntnose Minnow50.05
BNS26.81
MMS23.95
Bluegill23.180.13 lb
Yellow Perch15.660.1 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.

Bluegill

840 fish · 38 in · 2025-08-18
2101050345678

Yellow Perch

3 fish · 56 in · 2025-08-18
21056

From the 2025-08-18 survey

Grand Lake is a 655-acre, highly developed lake located approximately two miles south of Rockville in eastern Stearns County. The lake has moderate to good water quality with an average summer Secchi depth of 8.9 feet, reflecting improved water clarity since the last survey. It is classified as lake class 27. The…

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 Grand Lake. 3 reports on file.

EPA Impairment Status

Grand 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 MN73-0055-00 · Official waterbody report

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Lake details from Minnesota DNR LakeFinder

Ice data from Minnesota DNR Climate

Most recent sample: 2024-08-25

Monitoring stations: 3