Rock Lake
Crow Wing County, Minnesota203 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Rock Lake. Here is what has been measured.
- 22 ft max depth
- Public access
- Limited data
Rock Lake in Crow Wing County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.4 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 6.3 µg/L. Maximum depth: 22 ft. Surface area: 203.41 acres.
Minnesota DNR's Targeted Survey on July 20, 2022 caught 1.42 northern pike per hour of electrofishing at Rock Lake. DNR survey details →
Rock Lake is a 203-acre lake in Crow Wing County, Minnesota with a maximum depth of 22 feet. Overall water quality is improving over recent sampling years. The lake supports 17 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-08-09. Methodology: how these readings are compared.
What Rock Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing17 species recorded
- Ice seasonIce-out around Apr 10
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether 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 Rock Lake
These are the measurements Minnesota PCA publishes for Rock Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 7.4 ft. Phosphorus 18 µg/L. Chlorophyll-a 6.3 µg/L. TSI 48.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 18µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 6.3µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 48 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Rock Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Rock Lake typically sits around 67°F at the surface in September. Summer average is about 72°F. Usually warmest in Jul (about 74°F) and coldest in May (about 60°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (60°F) to its warmest (74°F).
Typical surface water temperature by month, from 38 field readings (2016–2024) via the EPA Water Quality Portal. See the full Rock Lake water temperature breakdown →
Minnesota DNR's Targeted Survey on July 20, 2022 caught 1.42 northern pike per hour of electrofishing at Rock Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rock Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2022-07-20 (Targeted Survey).
2 surveys on file · most recent 2022-07-20 (Targeted Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Green Sunfish | 97.83 | ||
| Largemouth Bass | 19.46 | 8 in 2022-06-06 | 0.34 lb |
| Bluegill | 15.25 | 3–8 in 2022-06-06 | 0.12 lb |
| Yellow Perch | 15.22 | 5–7 in 2022-06-06 | 0.07 lb |
| Bluntnose Minnow | 12.37 | ||
| Hybrid Sunfish | 8.34 | 4–7 in 2022-06-06 | 0.18 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.
Largemouth Bass
Bluegill
Yellow Perch
Hybrid Sunfish
From the 2022-07-20 survey
Rock Lake is a 203 acre lake, with a maximum depth of 22', located three miles south of Pine Center in Crow Wing County. Rock is in the Mississippi River-Sartell watershed. A nearshore survey was conducted to assess the populations of both game and non-game fish species. Ten 100' long sampling stations were evenly…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Rock Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — RockFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Rock (0209)Aquatic Plant Report · MN DNR LakeFinder
- —Aquatic Plant Report — Rock (2036)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — RockPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
22 ft
Surface area
203 acres
Shoreline
3.7 mi
Littoral zone
63%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
3 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,247 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Rock LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Rock Lake
Compare lakeside cabins, hotels, and vacation rentals near Rock Lake in Crow Wing 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 Rock Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Rock Lake
Water Quality Trend: Improving
Based on 4 years of monitoring (2020–2024).
Water clarity
Improving4 years
Ice season
Typical ice-out
Apr 10
Earliest Mar 11, 2024 · Latest May 10, 2022
Most recent ice-out
Mar 11
2024
10 observations · Minnesota PCA ice records
Nearby Lakes in Crow Wing County
Frequently asked questions about Rock Lake
Where is Rock Lake?
- Rock Lake is a lake in Crow Wing County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Rock Lake?
- Rock Lake in Crow Wing County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.4 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 6.3 µg/L. Maximum depth: 22 ft. Surface area: 203.41 acres.
Is Rock Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Rock Lake?
- Rock Lake typically sits around 67°F at the surface in September, from 38 EPA Water Quality Portal field readings (2016–2024). That is a typical value for the month, not a live reading.
How deep is Rock Lake?
- Rock Lake has a maximum depth of 22 feet. The lake covers 203.41 acres.
What fish are in Rock Lake?
- Fish species found in Rock Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, sunfish, walleye, white sucker, yellow bullhead, yellow perch. Rock Lake is located in Crow Wing County, Minnesota.
What did the DNR fisheries survey find at Rock Lake?
- Minnesota DNR's Targeted Survey on July 20, 2022 caught 1.42 northern pike per hour of electrofishing at Rock Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Rock Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
When does Rock Lake thaw?
- Rock Lake typically has ice-out around Apr 10.
Are there boat ramps on Rock Lake?
- Rock Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Rock Lake. Public access is listed as yes.
Can I fish at Rock Lake?
- 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 Rock Lake across LakeQuality
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Where this data comes from
19 measurements from 2 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA19 samples · 2020–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- 2120 B ~ Color in Water by Visual Comparison
Monitoring station identifiers (2)
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
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