Lily Lake
Lily Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.5 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 5.1 µg/L. Maximum depth: 51 ft. Surface area: 43.79 acres.
- Clarity
- 10.5 ft
- Typical in August
- 55°F
- Max depth
- 51 ft
- Area
- 44 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
Next lake in Washington County
Lily Lake is a 44-acre mesotrophic lake in Washington County, Minnesota with a maximum depth of 51 feet (18-foot average). Water quality is graded A based on 2 sampling years through 2025. The lake supports 10 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, Lily Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-23. 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 10.5 ft. Phosphorus level: 17 µg/L. Chlorophyll-a: 5.1 µg/L. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | Not graded |
| Phosphorus | 17 µg/L | Good |
| Chlorophyll-a (Algae) | 5.1 µg/L | Good |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lily Lake
Compare lakeside cabins, hotels, and vacation rentals near Lily 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
Lily Lake typically sits around 55°F at the surface in August. Summer average is about 53°F. Usually warmest in Sep (about 56°F) and coldest in Feb (about 37°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 425 field readings (2010–2025) via the EPA Water Quality Portal. See the full Lily Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 51 ft |
| Average Depth | 17.7 ft |
| Surface Area | 44 acres |
| Shoreline Length | 1.1 mi |
| Littoral Zone | 45% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Lily LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Lily Lake
DNR Fisheries Survey Summary
10 surveys on file from MN DNR Fisheries. Most recent: 2021-06-07 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 44.93 | 0.11 lb |
| Largemouth Bass | 12.09 | 0.9 lb |
| Hybrid Sunfish | 6.53 | 0.17 lb |
| Black Bullhead | 5.66 | 0.56 lb |
| Pumpkinseed | 4.24 | 0.12 lb |
| Yellow Perch | 3.83 | 0.12 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
Hybrid Sunfish
Black Bullhead
From the 2021-06-07 survey
Lily Lake is a 36 acre lake located in the City of Stillwater, Washington County. It has a littoral area of 19.7 acres, is in lake class 30, and has approximately one mile of shoreline with nearly 25% owned by the City of Stillwater and managed for recreational use. Lily Lake Park has a fishing pier, boat access…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lily Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — LilyFisheries Lake Survey · MN DNR LakeFinder
- —Public Water Access Sites — LilyPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.052 m/yr | 4 |
EPA Impairment Status
Lily 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 MN82-0023-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lily Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger.
- Met Council - St Croix Valley WwtpOak Park Heights · 1.7 mi away · NPDES MN0029998Major
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 #8 of 75 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Lily Lake
What is the water quality grade for Lily Lake?
- Lily Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.5 ft visibility. Phosphorus: 17 µg/L. Chlorophyll-a (algae): 5.1 µg/L. Maximum depth: 51 ft. Surface area: 43.79 acres.
Is Lily Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Lily Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 5.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Lily Lake?
- Lily Lake typically sits around 55°F at the surface in August, from 425 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Lily Lake?
- Lily Lake has a maximum depth of 51 feet and an average depth of 17.7 feet. The lake covers 43.79 acres.
What fish are in Lily Lake?
- Fish species found in Lily Lake include black crappie, bluegill, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white sucker, yellow perch. Lily Lake is located in Washington County, Minnesota.
Are there boat ramps on Lily Lake?
- Lily Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Lily Lake. Public access is listed as yes.
Explore Lily Lake across LakeGrade
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Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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Other Grade A Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Where this data comes from
65 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA65 samples · 2021–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
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 size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory