Third River Flowage Lake
Itasca County, Minnesota56,471 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Third River Flowage Lake. Here is what has been measured.
- Mesotrophic
- zebra mussel
- 70 ft max depth
- Public access
Third River Flowage Lake in Itasca County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6.9 ft visibility. Phosphorus: 28.5 µg/L. Chlorophyll-a (algae): 5.5 µg/L. Maximum depth: 69.8 ft. Surface area: 56471.4 acres.
Minnesota DNR's Standard Survey on April 16, 2025 caught 6.06 walleye per gill net at Third River Flowage Lake. Length samples in the latest survey that recorded them ran 1–25 inches. DNR survey details →
Third River Flowage Lake is a 56,471-acre mesotrophic lake in Itasca County, Minnesota with a maximum depth of 70 feet (15-foot average). Overall water quality is declining over recent sampling years. The lake supports 20 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 71 other monitored lakes in Itasca County, Third River Flowage Lake ranks #61 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-14. Methodology: how these readings are compared.
At about 56,000 acres, Third River Flowage Lake is large enough that where you stay decides which shore you see most of. It has one public boat landing. The median ice-out date is April 27, which is when the open-water season begins. For a place on the water, look through cabin and lake-house rentals near Third River Flowage Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Third River Flowage Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing20 species recorded
- Ice seasonIce-out around Apr 27
- Deep water69.8 ft surveyed max depth
- Big water56,471 acres
Swimming conditions
Readings onlyModerate 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 Third River Flowage Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Third River Flowage Lake
These are the measurements Minnesota PCA publishes for Third River Flowage Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 6.9 ft. Phosphorus 28.5 µg/L. Chlorophyll-a 5.5 µg/L. TSI 50.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 6.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 28.5µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 5.5µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 50 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Third River Flowage Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Third River Flowage Lake typically sits around 52°F at the surface in October. Summer average is about 69°F. Usually warmest in Jul (about 74°F) and coldest in Oct (about 52°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (52°F) to its warmest (74°F).
Typical surface water temperature by month, from 43 field readings (2024–2025) via the EPA Water Quality Portal. See the full Third River Flowage Lake water temperature breakdown →
Minnesota DNR's Standard Survey on April 16, 2025 caught 6.06 walleye per gill net at Third River Flowage Lake. Length samples in the latest survey that recorded them ran 1–25 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Third River Flowage Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
39 surveys on file from MN DNR Fisheries. Most recent: 2025-04-16 (Standard Survey).
39 surveys on file · most recent 2025-04-16 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Perch | 219.08 | 1–11 in 2025-04-16 | 0.19 lb |
| Spottail Shiner | 109.89 | ||
| Bluntnose Minnow | 22.18 | ||
| Walleye | 20.42 | 1–25 in 2025-04-16 | 1.19 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Yellow Perch
Walleye
From the 2025-04-16 survey
Lake Winnibigoshish, otherwise known as Winnie or Big Winnie, is a large reservoir located immediately north of the community of Bena, Minnesota. Winnie was a natural lake that was impounded in the 1880's with a dam controlled by the U.S. Army Corps of Engineers (USACE). Today the USACE maintains water levels within a…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Third River Flowage Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — WinnibigoshishFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Winnibigoshish (0702)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — WinnibigoshishFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — WinnibigoshishPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
69.8 ft
Average depth
15.1 ft
Surface area
56,471 acres
Shoreline
69.8 mi
Littoral zone
33%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Recreation & Access
- Third River FlowagePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Third River Flowage Lake
Compare lakeside cabins, hotels, and vacation rentals near Third River Flowage Lake in Itasca County, Minnesota — 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.
Top-rated places to stay near Third River Flowage Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 trip? Cabins and lodging at Third River Flowage Lake → · more Minnesota lake trips
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Fish Species
Click a species to see every lake where it is documented.
Fishing Third River Flowage Lake
- → Third River Flowage Lake fishing: DNR survey catch rates, species & stocking
- → Third River Flowage Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Third River Flowage Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Third River Flowage Lake? (mercury & PFAS guide)
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 readings over time
2 seasons of samples on record (2024–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Worsening+3.5 µg/L/yr2 years
Chlorophyll-a
Worsening+0.5 µg/L/yr2 years
Ice season
Typical ice-out
Apr 27
Earliest Mar 30, 2012 · Latest May 17, 2013
Most recent ice-out
Apr 29
2025
32 observations · Minnesota PCA ice records
Nearby Lakes in Itasca County
Frequently asked questions about Third River Flowage Lake
Where is Third River Flowage Lake?
- Third River Flowage Lake is a lake in Itasca County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Third River Flowage Lake?
- Third River Flowage Lake in Itasca County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6.9 ft visibility. Phosphorus: 28.5 µg/L. Chlorophyll-a (algae): 5.5 µg/L. Maximum depth: 69.8 ft. Surface area: 56471.4 acres.
Is Third River Flowage 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 Third River Flowage Lake?
- Third River Flowage Lake typically sits around 52°F at the surface in October, from 43 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Third River Flowage Lake?
- Third River Flowage Lake has a maximum depth of 69.8 feet and an average depth of 15.1 feet. The lake covers 56471.4 acres.
What fish are in Third River Flowage Lake?
- Fish species found in Third River Flowage Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, burbot, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, rock bass, shorthead redhorse, silver redhorse, sunfish, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Third River Flowage Lake is located in Itasca County, Minnesota.
What did the DNR fisheries survey find at Third River Flowage Lake?
- Minnesota DNR's Standard Survey on April 16, 2025 caught 6.06 walleye per gill net at Third River Flowage Lake. Length samples in the latest survey that recorded them ran 1–25 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Third River Flowage Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Third River Flowage Lake thaw?
- Third River Flowage Lake typically has ice-out around Apr 27.
Are there boat ramps on Third River Flowage Lake?
- Third River Flowage Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Third River Flowage. Public access is listed as yes.
Can I fish at Third River Flowage Lake?
- Third River Flowage 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 Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Third River Flowage Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Itasca County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
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Minnesota's cleanest lakes, ranked on agency measurements
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Compare Third River Flowage Lake With Nearby Lakes
Where this data comes from
42 measurements from 1 monitoring station, 2024–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Leech Lake Band of Ojibwe
LEECHLAK_WQX42 samples · 2024–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrate-Nitrite Nitrogen 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
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate