Rockstad Lake
Clearwater County, MinnesotaEutrophic
Rockstad Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. Rockstad Lake reaches 18 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 142 acres, Rockstad Lake fits the Minnesota median for monitored lakes, with 2.0 miles of shoreline. Within the 40 graded lakes of Clearwater County, Rockstad Lake sits at rank 39, near the bottom of the county list.
No invasive species are currently listed at Rockstad Lake — the lake remains off the Minnesota infested-waters roster. 4 fish species are on record, with panfish making up the recreational core. A documented public access point at Rockstad Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 4 ft. Phosphorus level: 48 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4 ft | D |
| Phosphorus | 48 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 18 ft |
| Surface Area | 141.52 acres |
| Shoreline Length | 2 mi |
| Littoral Zone | 86% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Rockstad Lake (14-day solunar calendar)
→ Is it safe to eat fish from Rockstad Lake? (mercury & PFAS guide)
→ Rockstad Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.01 m/yr | 4 |
| Phosphorus | ↓ Declining | +4.1 µg/L/yr | 5 |
Location
County Ranking
Ranked #39 of 40 lakes in Clearwater County
Cleaner Lakes Within 30 Miles
Rockstad Lake holds Grade C. 5 nearby lakes hold higher grades.
- ALong LakeClearwater County · mi · Two grade letters higher (C → A)
- AWaptus LakeClearwater County · mi · Two grade letters higher (C → A)
- AMckenzie LakeClearwater County · mi · Two grade letters higher (C → A)
- AIsland LakeClearwater County · mi · Two grade letters higher (C → A)
- ACesar LakeClearwater County · mi · Two grade letters higher (C → A)
Nearby Lakes in Clearwater County
More Minnesota Lake Rankings
State Parks Near Rockstad Lake
Other Grade C Lakes in Minnesota
Eutrophic Lakes in Minnesota
DNR Fisheries Survey Summary
5 surveys on file from MN DNR Fisheries. Most recent: 2014-08-11 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 148.28 | 0.2 lb |
| Yellow Perch | 144.66 | 0.16 lb |
| White Sucker | 11.79 | 0.87 lb |
| Brown Bullhead | 5.88 | 0.42 lb |
| Walleye | 5.77 | 0.43 lb |
| Northern Pike | 5.03 | 3.02 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
Yellow Perch
White Sucker
Brown Bullhead
From the 2014-08-11 survey
Rockstad Lake is a 128-acre lake with a maximum depth of 18 feet located near the town of Zerkel in southern Clearwater County. The Minnesota Department of Natural Resources has classified Minnesota's lakes into 43 different lake classes based on physical characteristics, water chemistry and fish community. Rockstad…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Rockstad Lake. 3 reports on file.
- —Fisheries Lake Survey — RockstadFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Rockstad (1693)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — RockstadPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Rockstad Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN15-0075-00 · 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
Most recent sample: 2024-09-10
Monitoring stations: 1