Elmo Lake
Washington County, MinnesotaLimited DataMesotrophic
On the LakeGrade scale Elmo Lake grades a B, with clarity at 11.2 ft and phosphorus readings still being added placing it above the Minnesota median.
A TSI near 42 places Elmo Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. At 140 ft of maximum depth, Elmo Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. At 257 acres, Elmo Lake fits the Minnesota median for monitored lakes, with 4.1 miles of shoreline. Among the 31 graded lakes in Washington County, Elmo Lake sits at rank 8, above the county median.
Eurasian watermilfoil is established at Elmo Lake, which can dampen recreational access and pressure the native plant community. Muskie are on the species list at Elmo Lake, among the lake's 13 documented fish. A documented public access point at Elmo Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 11.2 ft. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.2 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 140 ft |
| Average Depth | 31 ft |
| Surface Area | 256.82 acres |
| Shoreline Length | 4.1 mi |
| Littoral Zone | 17% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Elmo Lake (14-day solunar calendar)
→ Is it safe to eat fish from Elmo Lake? (mercury & PFAS guide)
→ Elmo 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 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.005 m/yr | 4 |
Ice Season
Historical ice data from Minnesota DNR (4 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-03-25 (2021) | 2018-04-30 (2018) |
| Ice-In | 2024-01-03 (2024) | 2024-01-03 (2024) |
Most recent ice-out: 2021-03-25
Location
County Ranking
Ranked #8 of 31 lakes in Washington County
Nearby Lakes in Washington County
More Minnesota Lake Rankings
State Parks Near Elmo Lake
Other Grade B Lakes in Minnesota
Mesotrophic Lakes in Minnesota
DNR Fisheries Survey Summary
18 surveys on file from MN DNR Fisheries. Most recent: 2025-08-06 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 22.95 | 0.1 lb |
| Largemouth Bass | 11.55 | 1.52 lb |
| Tullibee (Cisco) | 10.09 | 0.51 lb |
| Northern Pike | 4.45 | 3.02 lb |
| BCS | 4.05 | — |
| Yellow Perch | 3.72 | 0.1 lb |
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
Largemouth Bass
Tullibee (Cisco)
Northern Pike
From the 2025-08-06 survey
A targeted survey of nearshore fish species in Lake Elmo was conducted on August 6, 2025, by Lake Biological Monitoring and Assessment program staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Elmo Lake. 3 reports on file.
- —Fisheries Lake Survey — ElmoFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — ElmoFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ElmoPublic Water Access Sites · MN DNR LakeFinder
Reservoir Info (USACE NID)
Elmo Lake is a man-made reservoir impounded by the Lake Elmo Regional Park (completed 1981), built primarily for flood risk reduction on the Eagle Point Lake-TR; earth-type dam, 32 ft tall.
- Surface area
- 281 ac
- Normal storage
- 2 ac-ft
- Max storage
- 140 ac-ft
- Drainage area
- 20.3 sq mi
- Hazard class
- Low
- Owner
- WD of Valley Branch
Source: USACE National Inventory of Dams, NID ID MN00915 · Operator website
EPA Impairment Status
Elmo 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 MN82-0106-00 · 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: 2024-09-12
Monitoring stations: 1