Caldron Falls Reservoir
Marinette County, WisconsinLimited DataEutrophic
Caldron Falls Reservoir earns a D — measurements through 2024 show persistent nutrient pressure that limits clarity through the summer.
Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. A maximum depth of 40 ft puts Caldron Falls Reservoir in the middle of Wisconsin's depth distribution. Caldron Falls Reservoir covers 1,063 acres alongside partial shoreline records, large enough that conditions can vary meaningfully between bays. Within the 21 graded lakes of Marinette County, Caldron Falls Reservoir sits at rank 20, near the bottom of the county list.
Zebra mussel presence at Caldron Falls Reservoir means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. Walleye are documented at Caldron Falls Reservoir, one of 5 fish species on record for the lake. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-09-20. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Murky, only visible to about 5.2 ft. Trophic State Index: 53.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.2 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 53 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 40 ft |
| Surface Area | 1.1K acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Caldron Falls Reservoir (14-day solunar calendar)
→ Is it safe to eat fish from Caldron Falls Reservoir? (mercury & PFAS guide)
→ Caldron Falls Reservoir fishing regulations (limits, seasons, special rules)
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 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.062 m/yr | 3 |
Location
County Ranking
Ranked #20 of 21 lakes in Marinette County
Cleaner Lakes Within 30 Miles
Caldron Falls Reservoir holds Grade D. 5 nearby lakes hold higher grades.
- ABig Newton LakeMarinette County · mi · Two grade letters higher (D → A)
- AThunder LakeMarinette County · mi · Two grade letters higher (D → A)
- ALittle Newton LakeMarinette County · mi · Two grade letters higher (D → A)
- ABoundary LakeOconto County · mi · Two grade letters higher (D → A)
- BGilkey LakeOconto County · mi · Two grade letters higher (D → B)
Nearby Lakes in Marinette County
More Wisconsin Lake Rankings
State Parks Near Caldron Falls Reservoir
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Compare Caldron Falls Reservoir With Nearby Lakes
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 5 stations on file (most recent sample 2024).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Caldron Falls Reservoir covering fish populations, stocking, water quality, and management. 1 report on file.
- 2012Caldron Falls Flowage comprehensive fishery survey 2012Comprehensive Survey · WI DNR · 2012 (PDF)
Reservoir Info (USACE NID)
Caldron Falls Reservoir is a man-made reservoir impounded by the Caldron Falls (completed 1924), built primarily for hydroelectric on the Peshtigo River; gravity-type dam, 81 ft tall and 1,250 ft long.
- Surface area
- 1,018 ac
- Normal storage
- 11,475 ac-ft
- Max storage
- 11,500 ac-ft
- Drainage area
- 496 sq mi
- Hazard class
- High
- Owner
- Wisconsin Public Service Corporation
All listed purposes: Hydroelectric;Fish and Wildlife Pond;Recreation;Flood Risk Reduction.
Source: USACE National Inventory of Dams, NID ID WI00759 · Operator website
EPA Impairment Status
Caldron Falls Reservoir 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 WI10001685 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-20
Monitoring stations: 1