Ludden Lake
Ludden Lake in Iowa County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.5 ft visibility. Phosphorus: 172 µg/L. Maximum depth: 14 ft. Surface area: 56 acres.
- Clarity
- 1.5 ft
- Typical in July
- 74°F
- Max depth
- 14 ft
- Area
- 56 acres
- Type
- Hypereutrophic
- Trend
- ↓ Declining
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Ludden Lake →
Next lake in Iowa County
Ludden Lake is a 56-acre highly nutrient-loaded hypereutrophic lake in Iowa County, Wisconsin with a maximum depth of 14 feet. Water quality is graded D based on 1 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Smallmouth Bass. Public access is available with 1 public boat landing. Compared to the 5 other monitored lakes in Iowa County, Ludden Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-05-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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 1.5 ft of visibility. Phosphorus level: 172 µg/L. Trophic State Index: 75.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.5 ft | Not graded |
| Phosphorus | 172 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Ludden Lake
Compare lakeside cabins, hotels, and vacation rentals near Ludden Lake in Iowa 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 Ludden Lake are listed below.
Top-rated places to stay near Ludden Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Ludden Lake typically sits around 74°F at the surface in July. Summer average is about 76°F. Usually warmest in Jun (about 77°F) and coldest in Mar (about 42°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 16 field readings (2024–2025) via the EPA Water Quality Portal. See the full Ludden Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 14 ft |
| Surface Area | 56 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Ludden LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Ludden 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 1999. 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 Ludden Lake covering fish populations, stocking, water quality, and management. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2023Ludden Lake comprehensive survey 2023Comprehensive Survey · WI DNR · 2023 (PDF)
- 2013Ludden Lake comprehensive survey 2013Comprehensive Survey · WI DNR · 2013 (PDF)
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.025 m/yr | 5 |
| Phosphorus | ↓ Declining | +26.5 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Ludden Lake is a man-made reservoir impounded by the Ludden Lake (completed 1964), built primarily for recreation on the MINERAL POINT BRANCH; earth-type dam, 25 ft tall and 300 ft long.
- Surface area
- 58 ac
- Normal storage
- 303 ac-ft
- Max storage
- 700 ac-ft
- Drainage area
- 24 sq mi
- Hazard class
- Low
- Owner
- LUDDEN LAKE DAM COMMISSION
Source: USACE National Inventory of Dams, NID ID WI00069 · Operator website
EPA Impairment Status
Ludden Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10008359 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Ludden Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Mineral Point Wastewater Treatment FacilityMineral Point · 2.5 mi away · NPDES WI0024791Recent violation
- Linden Wastewater Treatment FacilityLinden · 3.7 mi away · NPDES WI0021580Recent violation
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 #4 of 6 lakes in Iowa County
Nearby Lakes With Higher Grades
Ludden 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.
Nearby Lakes in Iowa County
Frequently asked questions about Ludden Lake
What is the water quality grade for Ludden Lake?
- Ludden Lake in Iowa County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.5 ft visibility. Phosphorus: 172 µg/L. Maximum depth: 14 ft. Surface area: 56 acres.
Is Ludden 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. Ludden Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
What is the water temperature of Ludden Lake?
- Ludden Lake typically sits around 74°F at the surface in July, from 16 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Ludden Lake?
- Ludden Lake has a maximum depth of 14 feet. The lake covers 56 acres.
What fish are in Ludden Lake?
- Fish species found in Ludden Lake include Panfish, Largemouth Bass, Smallmouth Bass. Ludden Lake is located in Iowa County, Wisconsin.
Are there boat ramps on Ludden Lake?
- Ludden Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Ludden Lake. Public access is listed as yes.
Explore Ludden Lake across LakeGrade
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Where this data comes from
43 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_WQX43 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