Lilly Lake
Lilly Lake in Dakota County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2 ft visibility. Phosphorus: 145 µg/L. Chlorophyll-a (algae): 64 µg/L. Maximum depth: 8 ft. Surface area: 8.08 acres.
- Clarity
- 2 ft
- Max depth
- 8 ft
- Area
- 8 acres
- Type
- Hypereutrophic
- Trend
- ↓ Declining
- Public access
- No
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Lilly Lake →
Next lake in Dakota County
Lilly Lake is a 8-acre highly nutrient-loaded hypereutrophic lake in Dakota County, Minnesota with a maximum depth of 8 feet. Water quality is graded F based on 2 sampling years through 2024. 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 44 other monitored lakes in Dakota County, Lilly Lake ranks #45 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-05. 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.
Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom
Water Quality Grade: F (Algae-prone)
Very murky, less than 2 ft of visibility. Phosphorus level: 145 µg/L. Chlorophyll-a: 64 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 145 µg/L | Poor |
| Chlorophyll-a (Algae) | 64 µg/L | Poor |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Lilly Lake
Compare lakeside cabins, hotels, and vacation rentals near Lilly Lake in Dakota 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Lilly Lake are listed below.
Top-rated places to stay near Lilly Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8 ft |
| Surface Area | 8 acres |
| Shoreline Length | 0.5 mi |
| Littoral Zone | 87% |
| Public Access | No |
Fishing Lilly 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.
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.38 m/yr | 2 |
EPA Impairment Status
Lilly 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 MN19-0048-00 · Official waterbody report · Matched by proximity (0.4 km)
Regulated Pollution Sources Nearby
7 EPA-permitted facilities operate within about 5 miles of Lilly Lake under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 1 facility has a reported Clean Water Act violation in the past three years.
- Met Council - Metropolitan WwtpSaint Paul · 1.5 mi away · NPDES MN0029815Major
- Met Council - Mississippi Basin Total PhosphorusSaint Paul · 1.5 mi away · NPDES MN0070629Major
- Captain Ken'S Foods IncSaint Paul · 1.6 mi away · NPDES MN0059765Recent violation
- Magellan Pipeline MinneapolisSaint Paul, City Of · 0.6 mi away · NPDES MN0045896
- Saint Paul Port Authority-Multiple Dredge/Southport Terminal Storage SitesSaint Paul · 0.8 mi away · NPDES MN0056081
- Flint Hills Resources L.P.Saint Paul · 1.7 mi away · NPDES MN0064696
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 #45 of 45 lakes in Dakota County
Nearby Lakes With Higher Grades
Lilly Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Dakota County
Frequently asked questions about Lilly Lake
What is the water quality grade for Lilly Lake?
- Lilly Lake in Dakota County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 2 ft visibility. Phosphorus: 145 µg/L. Chlorophyll-a (algae): 64 µg/L. Maximum depth: 8 ft. Surface area: 8.08 acres.
Is Lilly Lake safe to swim in?
- Algae and nutrients are often high — check current advisories before swimming. Skip the water if you see scum or a paint-like bloom. Lilly Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 64 µg/L. Always check local health department advisories before swimming.
How deep is Lilly Lake?
- Lilly Lake has a maximum depth of 8 feet. The lake covers 8.08 acres.
Explore Lilly Lake across LakeGrade
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Species activity outlook by water temperature and season
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Very high nutrients, dense algae, poor clarity
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Where this data comes from
28 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA28 samples · 2024
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 details from Minnesota DNR LakeFinder