Idlewild Lake
Idlewild Lake in Hennepin County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.2 ft visibility. Phosphorus: 36 µg/L. Chlorophyll-a (algae): 6.9 µg/L. Maximum depth: 9 ft. Surface area: 12.81 acres.
- Clarity
- 6.2 ft
- Typical in August
- 75°F
- Max depth
- 9 ft
- Area
- 13 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- No
Next lake in Hennepin County
Idlewild Lake is a 13-acre productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota with a maximum depth of 9 feet. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Idlewild Lake ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-18. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 6.2 ft. Phosphorus level: 36 µg/L. Chlorophyll-a: 6.9 µg/L. Trophic State Index: 52.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 ft | Not graded |
| Phosphorus | 36 µg/L | Fair |
| Chlorophyll-a (Algae) | 6.9 µg/L | Good |
| Trophic State Index (TSI) | 52 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Idlewild Lake
Compare lakeside cabins, hotels, and vacation rentals near Idlewild Lake in Hennepin 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.
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Water Temperature
Idlewild Lake typically sits around 75°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 78°F) and coldest in Jan (about 38°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 139 field readings (2022–2025) via the EPA Water Quality Portal. See the full Idlewild Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 9 ft |
| Surface Area | 13 acres |
| Shoreline Length | 0.7 mi |
| Littoral Zone | 100% |
| Public Access | No |
Fishing Idlewild Lake
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1992-06-15 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 67.60 | 0.21 lb |
| Black Bullhead | 32.00 | 0.41 lb |
| Hybrid Sunfish | 26.40 | 0.24 lb |
| Black Crappie | 11.20 | 0.06 lb |
| GOS | 7.70 | 0.1 lb |
| Pumpkinseed | 7.30 | 0.19 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 1992-06-15 survey
CEN, BLB, AND GOS DOMINATE THE FISH POPULATION. LMB WERE SAMPLED IN NUMBERS 4.8 TIMES THE LOCAL MEDIAN AND 4 TIMES THE STATE MEDIAN FOR GILLNETS; 5.9 TIMES THE LOCAL MEDIAN AND 2.9 TIMES THE STATE MEDIAN FOR TRAPNETS. ELECTROFISHING CAPTURED 26 LMB. AGE AND GROWTH ANALYSIS INDICATED THE PRESENCE OF FISH IN AGE-CLASSES…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Idlewild Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — IdlewildFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.067 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.78 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +1.02 µg/L/yr | 6 |
EPA Impairment Status
Idlewild Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN27-0073-00 · Official waterbody report · Matched by proximity (1.3 km)
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Idlewild Lake under Clean Water Act (NPDES) discharge permits.
- Emerson Process ManagementEden Prairie · 0.3 mi away · NPDES MN0054747
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 #14 of 81 lakes in Hennepin County
Nearby Lakes in Hennepin County
Frequently asked questions about Idlewild Lake
What is the water quality grade for Idlewild Lake?
- Idlewild Lake in Hennepin County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.2 ft visibility. Phosphorus: 36 µg/L. Chlorophyll-a (algae): 6.9 µg/L. Maximum depth: 9 ft. Surface area: 12.81 acres.
Is Idlewild Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Idlewild Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 6.9 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Idlewild Lake?
- Idlewild Lake typically sits around 75°F at the surface in August, from 139 EPA Water Quality Portal field readings (2022–2025). That is a typical value for the month, not a live reading.
How deep is Idlewild Lake?
- Idlewild Lake has a maximum depth of 9 feet. The lake covers 12.81 acres.
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Where this data comes from
171 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
MNPCA171 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)
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 details from Minnesota DNR LakeFinder