Flannery Lake
Oneida County, Wisconsin107 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Flannery Lake. Here is what has been measured.
- Oligotrophic
- 35 ft max depth
- Public access
Flannery Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 14.5 ft visibility. Phosphorus: 12.7 µg/L. Maximum depth: 35 ft. Surface area: 107 acres.
Wisconsin DNR lists Panfish as common on Flannery Lake. DNR survey details →
Flannery Lake is a 107-acre cold, clear oligotrophic lake in Oneida County, Wisconsin with a maximum depth of 35 feet. Overall water quality is improving over recent sampling years. The lake supports 2 documented fish species including Panfish and Largemouth Bass. Public access is available with 1 public boat landing. Compared to the 66 other monitored lakes in Oneida County, Flannery Lake ranks #25 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-29. Methodology: how these readings are compared.
What Flannery Lake is good for
From access and monitoring records, not editorial picks.
- Clear water14.5 ft of visibility
- Boat launch1 documented ramp
- Deep water35 ft surveyed max depth
Swimming conditions
Readings onlyLow algae
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. Check local advisories before you swim.
Whether Flannery Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Flannery Lake
These are the measurements Wisconsin DNR publishes for Flannery 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 12.7 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 | 12.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 40 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Flannery Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Flannery Lake typically sits around 65°F at the surface in September. Summer average is about 71°F. Usually warmest in Aug (about 75°F) and coldest in Sep (about 65°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (65°F) to its warmest (75°F).
Typical surface water temperature by month, from 10 field readings (2024–2025) via the EPA Water Quality Portal. See the full Flannery Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Flannery Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Flannery Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2005. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
35 ft
Surface area
107 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- Flannery 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 Flannery Lake
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Top-rated places to stay near Flannery Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Flannery Lake
Water Quality Trend: Improving
Based on 7 years of monitoring (2020–2026).
Water clarity
Stable7 years
Phosphorus
Improving-0.35 µg/L/yr6 years
Nearby Lakes in Oneida County
Frequently asked questions about Flannery Lake
Where is Flannery Lake?
- Flannery Lake is a lake in Oneida County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Flannery Lake?
- Flannery Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 14.5 ft visibility. Phosphorus: 12.7 µg/L. Maximum depth: 35 ft. Surface area: 107 acres.
Is Flannery Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Flannery Lake?
- Flannery Lake typically sits around 65°F at the surface in September, from 10 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Flannery Lake?
- Flannery Lake has a maximum depth of 35 feet. The lake covers 107 acres.
What fish are in Flannery Lake?
- Fish species found in Flannery Lake include Panfish, Largemouth Bass. Flannery Lake is located in Oneida County, Wisconsin.
What did the DNR fisheries survey find at Flannery Lake?
- Wisconsin DNR lists Panfish as common on Flannery Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Flannery Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Flannery Lake?
- Flannery Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Flannery Lake. Public access is listed as yes.
Can I fish at Flannery Lake?
- Flannery 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 Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Flannery Lake across LakeQuality
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Where this data comes from
44 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX44 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
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
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory