Long Lake
Long Lake in Manitowoc County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.9 ft visibility. Phosphorus: 90.4 µg/L. Maximum depth: 38 ft. Surface area: 119 acres.
- Clarity
- 1.9 ft
- Max depth
- 38 ft
- Area
- 119 acres
- 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 Long Lake →
Next lake in Manitowoc County
Long Lake is a 119-acre productive, nutrient-rich eutrophic lake in Manitowoc County, Wisconsin with a maximum depth of 38 feet. Water quality is graded D based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 2 public boat landings. Compared to the 15 other monitored lakes in Manitowoc County, Long Lake ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-25. Grade methodology: LakeGrade methodology.
Watch Long Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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)
Very murky, less than 1.9 ft of visibility. Phosphorus level: 90.4 µg/L. Trophic State Index: 68.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.9 ft | Not graded |
| Phosphorus | 90.4 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long 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 Long Lake are listed below.
Top-rated places to stay near Long Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 38 ft |
| Surface Area | 119 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Round LakePublic
- Long LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1992. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Long Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2017Long Lake comprehensive survey 2017Comprehensive Survey · WI DNR · 2017 (PDF)
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.116 m/yr | 6 |
| Phosphorus | ↑ Improving | -2.85 µg/L/yr | 6 |
EPA Impairment Status
Long 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 WI10006082 · Official waterbody report
Regulated Pollution Sources Nearby
7 EPA-permitted facilities operate within about 5 miles of Long Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Brillion Wastewater TreatmentBrillion · 2.5 mi away · NPDES WI0020443Recent violation
- Forest Junction UtilityBrillion · 3.5 mi away · NPDES WI0032123Recent violation
- Reedsville Wastewater TreatmenReedsville · 4.5 mi away · NPDES WI0021342Recent violation
- Kocourek Bros PartnershipMaple Grove, Town Of · 2.2 mi away · NPDES WI0065871
- Brillion Iron Works IncBrillion · 3.2 mi away · NPDES WI0000761
- Sunny Slope Dairy LlcMaple Grove, Town Of · 3.8 mi away · NPDES WI0066206
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 #12 of 16 lakes in Manitowoc County
Nearby Lakes With Higher Grades
Long 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 Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Manitowoc County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.9 ft visibility. Phosphorus: 90.4 µg/L. Maximum depth: 38 ft. Surface area: 119 acres.
Is Long 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. Long Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
How deep is Long Lake?
- Long Lake has a maximum depth of 38 feet. The lake covers 119 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include Panfish, Largemouth Bass, Northern Pike. Long Lake is located in Manitowoc County, Wisconsin.
Are there boat ramps on Long Lake?
- Long Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Round Lake, Long Lake. Public access is listed as yes.
Explore Long Lake across LakeGrade
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Manitowoc County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the Sheboygan-Manitowoc, ranked by water quality
High nutrients, frequent algae, reduced clarity
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
State Parks Near Long Lake
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Where this data comes from
42 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX42 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory