Mccarthy Lake
Mccarthy Lake in Dakota County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1 ft visibility. Phosphorus: 195 µg/L. Chlorophyll-a (algae): 169.5 µg/L. Maximum depth: 19 ft. Surface area: 12.01 acres.
- Clarity
- 1 ft
- Typical in August
- 74°F
- Max depth
- 19 ft
- Area
- 12 acres
- Type
- Hypereutrophic
- Trend
- ↓ Declining
- Public access
- No
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Mccarthy Lake →
Next lake in Dakota County
Mccarthy Lake is a 12-acre highly nutrient-loaded hypereutrophic lake in Dakota County, Minnesota with a maximum depth of 19 feet (12-foot average). Water quality is graded F based on 2 sampling years through 2023. Overall water quality is declining over recent sampling years. The lake supports 6 documented fish species including black bullhead, black crappie, and bluegill. No public access — the lake is private or restricted. Compared to the 44 other monitored lakes in Dakota County, Mccarthy Lake ranks #40 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-09-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyAlgae risk
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
Water Quality Grade: F (Algae-prone)
Very murky, less than 1 ft of visibility. Phosphorus level: 195 µg/L. Chlorophyll-a: 169.5 µg/L. Trophic State Index: 79.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | 195 µg/L | Poor |
| Chlorophyll-a (Algae) | 169.5 µg/L | Poor |
| Trophic State Index (TSI) | 79 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Mccarthy Lake
Compare lakeside cabins, hotels, and vacation rentals near Mccarthy Lake in Dakota 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 Mccarthy Lake are listed below.
Top-rated places to stay near Mccarthy Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Mccarthy Lake typically sits around 74°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in Sep (about 66°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 36 field readings (2016–2023) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 19 ft |
| Average Depth | 11.9 ft |
| Surface Area | 12 acres |
| Shoreline Length | 0.6 mi |
| Littoral Zone | 70% |
| Public Access | No |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Mccarthy Lake
DNR Fisheries Survey Summary
6 surveys on file from MN DNR Fisheries. Most recent: 2022-06-23 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Largemouth Bass | 36.84 | 1.03 lb |
| Black Bullhead | 23.67 | 0.39 lb |
| Bluegill | 14.29 | 0.13 lb |
| Black Crappie | 8.62 | 0.15 lb |
| GOS | 6.60 | 0.11 lb |
| Channel Catfish | 3.92 | 2 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
Black Bullhead
Bluegill
Black Crappie
From the 2022-06-23 survey
Carlson Lake (19-0066-00), as it's now officially known is located in the city of Eagan. The lake drops off rather quickly to a maximum of 19 feet with approximately 26% of the surface area over 15 feet. Although an aeration system is operated (as needed) to prevent winterkill, city staff report it is not often…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Mccarthy Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — CarlsonFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — CarlsonFish Stocking History · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.006 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.67 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.23 µg/L/yr | 6 |
EPA Impairment Status
Mccarthy 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 MN19-0066-00 · Official waterbody report · Matched by proximity (1.28 km)
County Ranking
Ranked #40 of 45 lakes in Dakota County
Nearby Lakes With Higher Grades
Mccarthy Lake holds Grade F. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Dakota County
Frequently asked questions about Mccarthy Lake
What is the water quality grade for Mccarthy Lake?
- Mccarthy Lake in Dakota County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1 ft visibility. Phosphorus: 195 µg/L. Chlorophyll-a (algae): 169.5 µg/L. Maximum depth: 19 ft. Surface area: 12.01 acres.
Is Mccarthy 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. Mccarthy Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 169.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Mccarthy Lake?
- Mccarthy Lake typically sits around 74°F at the surface in August, from 36 EPA Water Quality Portal field readings (2016–2023). That is a typical value for the month, not a live reading.
How deep is Mccarthy Lake?
- Mccarthy Lake has a maximum depth of 19 feet and an average depth of 11.9 feet. The lake covers 12.01 acres.
What fish are in Mccarthy Lake?
- Fish species found in Mccarthy Lake include black bullhead, black crappie, bluegill, hybrid sunfish, largemouth bass, walleye. Mccarthy Lake is located in Dakota County, Minnesota.
Explore Mccarthy Lake across LakeGrade
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Where this data comes from
53 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA53 samples · 2021–2023
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity, Nephelometric Method
Monitoring station identifiers (1)
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 details from Minnesota DNR LakeFinder