Carstens Lake
Carstens Lake in Manitowoc County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 5.2 ft visibility. Phosphorus: 89.7 µg/L.
- Clarity
- 5.2 ft
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Carstens Lake →
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Carstens Lake is a productive, nutrient-rich eutrophic lake in Manitowoc County, Wisconsin. Water quality is graded D based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 15 other monitored lakes in Manitowoc County, Carstens Lake ranks #16 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-22. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyElevated nutrients
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 5.2 ft. Phosphorus level: 89.7 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.2 ft | Not graded |
| Phosphorus | 89.7 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Carstens Lake
Compare lakeside cabins, hotels, and vacation rentals near Carstens Lake in Manitowoc County, Wisconsin — 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 Carstens Lake are listed below.
Top-rated places to stay near Carstens Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Recreation & Access
- Carstens LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Carstens Lake
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -12.89 µg/L/yr | 7 |
EPA Impairment Status
Carstens 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 WI10000132 · Official waterbody report
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Carstens Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Grotegut Dairy Farm IncNewton · 2.1 mi away · NPDES WI0056847Recent violation
- Maple Leaf Dairy IncCleveland · 5 mi away · NPDES WI0058602Recent violation
- A H Stock Mfg & Stocks Dnr CluNewton · 2.4 mi away · NPDES WI0030341
- Glacier Rock Enterprises, Inc.Newton · 2.5 mi away · NPDES WI0058581
- Newton Meats And SausageNewton · 2.8 mi away · NPDES WI0042650
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #16 of 16 lakes in Manitowoc County
Nearby Lakes With Higher Grades
Carstens Lake holds Grade D. 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 Manitowoc County
Frequently asked questions about Carstens Lake
Where is Carstens Lake?
- Carstens Lake is a lake in Manitowoc County, Wisconsin. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Carstens Lake?
- Carstens Lake in Manitowoc County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 5.2 ft visibility. Phosphorus: 89.7 µg/L.
Is Carstens Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Carstens Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
Are there boat ramps on Carstens Lake?
- Carstens Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Carstens Lake. Public access is listed as yes.
Explore Carstens Lake across LakeQuality
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
28 measurements from 2 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX28 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory