Lost Lake
Cass County, Minnesota69 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Lost Lake. Here is what has been measured.
- Oligotrophic
- 26 ft max depth
Lost Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 14.8 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 2.3 µg/L. Maximum depth: 26 ft. Surface area: 68.5 acres.
Minnesota DNR's Standard Survey on July 12, 1990 caught 13.50 northern pike per gill net at Lost Lake. DNR survey details →
Lost Lake is a 69-acre cold, clear oligotrophic lake in Cass County, Minnesota with a maximum depth of 26 feet. Water clarity is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 103 other monitored lakes in Cass County, Lost Lake ranks #50 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-29. Methodology: how these readings are compared.
What Lost Lake is good for
From access and monitoring records, not editorial picks.
- Clear water14.8 ft of visibility
- Ice seasonIce-out around Apr 15
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 Lost 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 Lost Lake
These are the measurements Minnesota PCA publishes for Lost 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 14.8 ft. Phosphorus 10.5 µg/L. Chlorophyll-a 2.3 µg/L. TSI 38.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 14.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 10.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.3µg/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. | 38 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Lost Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lost Lake typically sits around 72°F at the surface in September. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (63°F) to its warmest (78°F).
Typical surface water temperature by month, from 51 field readings (2011–2024) via the EPA Water Quality Portal. See the full Lost Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 12, 1990 caught 13.50 northern pike per gill net at Lost Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lost Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1990-07-12 (Standard Survey).
1 survey on file · most recent 1990-07-12 (Standard Survey)
36 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 12.63 | 0.2 lb | |
| Black Bullhead | 9.50 | 0.6 lb | |
| Northern Pike | 7.00 | 1.05 lb | |
| Yellow Bullhead | 4.13 | 0.35 lb | |
| Rock Bass | 2.25 | 0.33 lb | |
| Pumpkinseed | 1.50 | 0.15 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.
From the 1990-07-12 survey
The northern pike gillnet catch of 13.5 is high. Most of the fish sampled were less than 20 inches long, but fish 30 inches long were collected. The northern pike growth rate is near the statewide average.The bluegill trapnet catch was 23.8. The sample collected exhibited fair quality indices - PSD=54; RSD-7=19;…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lost Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LostFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
26 ft
Surface area
69 acres
Shoreline
2.5 mi
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
17 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,325 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Lost Lake
Compare lakeside cabins, hotels, and vacation rentals near Lost Lake in Cass 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 Lost Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Follow Lost Lake’s readings
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Fishing Lost Lake
Water Quality Trend: Stable
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Phosphorus
Stable+0.07 µg/L/yr6 years
Chlorophyll-a
Worsening+0.17 µg/L/yr6 years
Ice season
Typical ice-out
Apr 15
Earliest Mar 31, 2016 · Latest Apr 30, 2008
Typical ice-in
Nov 20
Earliest Nov 10, 2017 · Latest Nov 27, 2007
Most recent ice-out
Apr 4
2017
20 observations · Minnesota PCA ice records
Nearby Lakes in Cass County
Frequently asked questions about Lost Lake
Where is Lost Lake?
- Lost Lake is a lake in Cass County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Lost Lake?
- Lost Lake in Cass County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 14.8 ft visibility. Phosphorus: 10.5 µg/L. Chlorophyll-a (algae): 2.3 µg/L. Maximum depth: 26 ft. Surface area: 68.5 acres.
Is Lost 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 Lost Lake?
- Lost Lake typically sits around 72°F at the surface in September, from 51 EPA Water Quality Portal field readings (2011–2024). That is a typical value for the month, not a live reading.
How deep is Lost Lake?
- Lost Lake has a maximum depth of 26 feet. The lake covers 68.5 acres.
What did the DNR fisheries survey find at Lost Lake?
- Minnesota DNR's Standard Survey on July 12, 1990 caught 13.50 northern pike per gill net at Lost Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Lost Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
When does Lost Lake thaw?
- Lost Lake typically has ice-out around Apr 15. Ice typically forms around Nov 20. The open water season is approximately 219 days.
Can I fish at Lost Lake?
- Public access to Lost Lake is listed as no on the lake record, so confirm before you make the trip. 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 Lost Lake across LakeQuality
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Where this data comes from
110 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA110 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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 size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate