Ely Lake
St. Louis County, MinnesotaOligotrophic
Ely Lake earns an A — every scored parameter (clarity and phosphorus) rates among the best monitored waters in St. Louis County. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.
A TSI value of 35 puts Ely Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. At 70 ft of maximum depth, Ely Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 723 acres, Ely Lake fits the Minnesota median for monitored lakes, with 9.6 miles of shoreline. Ely Lake ranks 21 of 187 in St. Louis County, putting it in the upper tier of locally monitored lakes.
Zebra mussel presence at Ely Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye among the lake's 14 documented species — a notable draw for Minnesota anglers. A documented public access point at Ely Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been logged at Ely Lake more than two dozen times, putting the median around Apr 24 — a useful baseline for tracking climate trends. 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, Minnesota DNR LakeFinder, last sampled 2024-10-01. Grade methodology: LakeGrade methodology.
Track Ely Lake
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 16 ft down. Phosphorus level: 7 µg/L. Trophic State Index: 35.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16 ft | A |
| Phosphorus | 7 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 35 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 70 ft |
| Surface Area | 723.09 acres |
| Shoreline Length | 9.6 mi |
| Littoral Zone | 31% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Ely Lake (14-day solunar calendar)
→ Is it safe to eat fish from Ely Lake? (mercury & PFAS guide)
→ Ely Lake 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 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.071 m/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (74 observations).
Estimated open water season: 214 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2000-04-05 (2000) | 1996-05-09 (1996) |
| Ice-In | 1991-11-05 (1991) | 2018-12-20 (2018) |
Most recent ice-out: 2022-05-06
Location
County Ranking
Ranked #21 of 187 lakes in St. Louis County
Nearby Lakes in St. Louis County
More Minnesota Lake Rankings
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Compare Ely Lake With Nearby Lakes
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2025-08-25 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 21.38 | 0.14 lb |
| Bluntnose Minnow | 14.57 | — |
| Hybrid Sunfish | 9.28 | 0.31 lb |
| Largemouth Bass | 8.32 | 0.58 lb |
| CNM | 6.43 | — |
| JND | 6.02 | — |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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.
Bluegill
Hybrid Sunfish
Largemouth Bass
From the 2025-08-25 survey
A targeted survey of nearshore fish species in Ely Lake was conducted on August 25th-August 28th, 2025, by Lake Biological Monitoring and Assessment (LBMA) program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing, mini-fyke nets, and seining with a 50-foot or…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Ely Lake. 4 reports on file.
- —Fisheries Lake Survey — ElyFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Ely (1771)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — ElyFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ElyPublic Water Access Sites · MN DNR LakeFinder
Reservoir Info (USACE NID)
Ely Lake is a man-made reservoir impounded by the Ely Lake (completed 1939), built primarily for recreation on the Ely Creek; gravity-type dam, 8 ft tall and 34 ft long.
- Surface area
- 780 ac
- Normal storage
- 55,620 ac-ft
- Max storage
- 61,182 ac-ft
- Drainage area
- 10 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN00005 · Operator website
EPA Impairment Status
Ely Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN69-0660-00 · 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
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate
Most recent sample: 2024-10-01
Monitoring stations: 3