Big Carnelian Lake
Washington County, Minnesota457 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Big Carnelian Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- zebra mussel
- 66 ft max depth
- Public access
- Limited data
Big Carnelian Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 14.5 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.4 µg/L. Maximum depth: 66 ft. Surface area: 457.03 acres.
Minnesota DNR's Standard Survey on August 4, 2025 caught 1.25 walleye per gill net at Big Carnelian Lake. DNR survey details →
Big Carnelian Lake is a 457-acre mesotrophic lake in Washington County, Minnesota with a maximum depth of 66 feet (26-foot average). The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 74 other monitored lakes in Washington County, Big Carnelian Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-30. Methodology: how these readings are compared.
Big Carnelian Lake covers about 460 acres in Washington County. It has one public boat landing. The median ice-out date is April 9, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Big Carnelian Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Big Carnelian Lake is good for
From access and monitoring records, not editorial picks.
- Clear water14.5 ft of visibility
- Boat launch1 documented ramp
- Fishing12 species recorded
- Ice seasonIce-out around Apr 9
- Deep water66 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
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. Big Carnelian Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Big Carnelian 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 Big Carnelian Lake
These are the measurements Minnesota PCA publishes for Big Carnelian Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 14.5 ft. Phosphorus 12 µg/L. Chlorophyll-a 3.4 µg/L. TSI 40.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 14.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 12µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 3.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 40 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Big Carnelian Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Big Carnelian Lake typically sits around 71°F at the surface in September. Summer average is about 73°F. Usually warmest in Aug (about 77°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (62°F) to its warmest (77°F).
Typical surface water temperature by month, from 31 field readings (2022–2025) via the EPA Water Quality Portal. See the full Big Carnelian Lake water temperature breakdown →
Minnesota DNR's Standard Survey on August 4, 2025 caught 1.25 walleye per gill net at Big Carnelian Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Carnelian Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
15 surveys on file from MN DNR Fisheries. Most recent: 2025-08-04 (Standard Survey).
15 surveys on file · most recent 2025-08-04 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluntnose Minnow | 98.44 | ||
| Bluegill | 32.25 | 3–9 in 2025-08-04 | 0.13 lb |
| Largemouth Bass | 7.07 | 5–17 in 2025-08-04 | 0.74 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.
Bluegill
Largemouth Bass
From the 2025-08-04 survey
Big Carnelian Lake is a 457-acre, class 24 lake located in northern Washington County. Northern Pike is the primary management species in Big Carnelian Lake while Walleye and Largemouth Bass are secondary management species. A previously instituted 24-36 inch protected slot length for Northern Pike was dropped in 2020…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Carnelian Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Big CarnelianFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Big CarnelianFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Big CarnelianPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
66 ft
Average depth
26 ft
Surface area
457 acres
Shoreline
5.1 mi
Littoral zone
29%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Recreation & Access
- Big Carnelian LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Big Carnelian Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Carnelian Lake in Washington 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 Big Carnelian Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fish Species
Click a species to see every lake where it is documented.
Fishing Big Carnelian Lake
- → Big Carnelian Lake fishing: DNR survey catch rates, species & stocking
- → Big Carnelian Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Big Carnelian Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Big Carnelian 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: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Ice season
Typical ice-out
Apr 9
Earliest Mar 10, 2024 · Latest Apr 23, 2008
Typical ice-in
Dec 7
Earliest Dec 2, 2003 · Latest Jan 15, 2024
Most recent ice-out
Mar 28
2025
34 observations · Minnesota PCA ice records
EPA Impairment Status
Big Carnelian 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.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN82-0049-00 · Official waterbody report
Nearby Lakes in Washington County
Frequently asked questions about Big Carnelian Lake
Where is Big Carnelian Lake?
- Big Carnelian Lake is a lake in Washington County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Big Carnelian Lake?
- Big Carnelian Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 14.5 ft visibility. Phosphorus: 12 µg/L. Chlorophyll-a (algae): 3.4 µg/L. Maximum depth: 66 ft. Surface area: 457.03 acres.
Is Big Carnelian Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Big Carnelian Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Big Carnelian Lake?
- Big Carnelian Lake typically sits around 71°F at the surface in September, from 31 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.
How deep is Big Carnelian Lake?
- Big Carnelian Lake has a maximum depth of 66 feet and an average depth of 26 feet. The lake covers 457.03 acres.
What fish are in Big Carnelian Lake?
- Fish species found in Big Carnelian Lake include black bullhead, black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow bullhead, yellow perch. Big Carnelian Lake is located in Washington County, Minnesota.
What did the DNR fisheries survey find at Big Carnelian Lake?
- Minnesota DNR's Standard Survey on August 4, 2025 caught 1.25 walleye per gill net at Big Carnelian Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Big Carnelian Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
When does Big Carnelian Lake thaw?
- Big Carnelian Lake typically has ice-out around Apr 9. Ice typically forms around Dec 7. The open water season is approximately 242 days.
Are there boat ramps on Big Carnelian Lake?
- Big Carnelian Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Carnelian Lake. Public access is listed as yes.
Can I fish at Big Carnelian Lake?
- Big Carnelian 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 Big Carnelian Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
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Where this data comes from
167 measurements from 2 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
MNPCA167 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
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
Impairment status from EPA ATTAINS 303(d) database
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate