Elmo Lake
Elmo Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.1 ft visibility. Phosphorus: 12.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Maximum depth: 140 ft. Surface area: 256.82 acres.
- Clarity
- 11.1 ft
- Typical in August
- 52°F
- Max depth
- 140 ft
- Area
- 257 acres
- Type
- Oligotrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Apr 8
Next lake in Washington County
Elmo Lake is a 257-acre cold, clear oligotrophic lake in Washington County, Minnesota with a maximum depth of 140 feet (31-foot average). Water quality is graded A based on 2 sampling years through 2025. The lake supports 13 documented fish species including black crappie, bluegill, and green sunfish. Public access is available with 1 public boat landing. Compared to the 74 other monitored lakes in Washington County, Elmo Lake ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.1 ft. Phosphorus level: 12.5 µg/L. Chlorophyll-a: 1.6 µg/L. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.1 ft | Not graded |
| Phosphorus | 12.5 µg/L | Good |
| Chlorophyll-a (Algae) | 1.6 µg/L | Good |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Elmo Lake
Compare lakeside cabins, hotels, and vacation rentals near Elmo Lake in Washington 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
Elmo Lake typically sits around 52°F at the surface in August. Summer average is about 63°F. Usually warmest in Jul (about 80°F) and coldest in Apr (about 40°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 598 field readings (2010–2025) via the EPA Water Quality Portal. See the full Elmo Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 140 ft |
| Average Depth | 31 ft |
| Surface Area | 257 acres |
| Shoreline Length | 4.1 mi |
| Littoral Zone | 17% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lake ElmoPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Elmo Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
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.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —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
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.024 m/yr | 5 |
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
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
County Ranking
Ranked #10 of 75 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Elmo Lake
What is the water quality grade for Elmo Lake?
- Elmo Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.1 ft visibility. Phosphorus: 12.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Maximum depth: 140 ft. Surface area: 256.82 acres.
Is Elmo Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Elmo Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 1.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Elmo Lake?
- Elmo Lake typically sits around 52°F at the surface in August, from 598 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Elmo Lake?
- Elmo Lake has a maximum depth of 140 feet and an average depth of 31 feet. The lake covers 256.82 acres.
What fish are in Elmo Lake?
- Fish species found in Elmo Lake include black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, smallmouth bass, tiger muskellunge, tullibee (cisco), walleye, white sucker, yellow perch. Elmo Lake is located in Washington County, Minnesota.
When does Elmo Lake thaw?
- Elmo Lake typically has ice-out around Apr 8.
Are there boat ramps on Elmo Lake?
- Elmo Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lake Elmo. Public access is listed as yes.
Explore Elmo Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
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Where this data comes from
38 measurements from 2 monitoring stations, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA38 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate