Sylvan Lake
Sylvan Lake in Hennepin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.2 ft visibility. Phosphorus: 296.6 µg/L. Chlorophyll-a (algae): 84.6 µg/L.
- Clarity
- 1.2 ft
- Typical in August
- 72°F
- Mean depth
- ~8 ft est.
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- No
Grade F measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Sylvan Lake →
Next lake in Hennepin County
Sylvan Lake is a highly nutrient-loaded hypereutrophic lake in Hennepin County, Minnesota with an estimated average depth of about 8 feet. Water quality is graded F based on 3 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Sylvan Lake ranks #74 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-01. Grade methodology: LakeGrade methodology.
Watch Sylvan Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Grade onlyAlgae risk
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 1.2 ft of visibility. Phosphorus level: 296.6 µg/L. Chlorophyll-a: 84.6 µg/L. Trophic State Index: 78.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.2 ft | Not graded |
| Phosphorus | 296.6 µg/L | Poor |
| Chlorophyll-a (Algae) | 84.6 µg/L | Poor |
| Trophic State Index (TSI) | 78 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Sylvan Lake
Compare lakeside cabins, hotels, and vacation rentals near Sylvan Lake in Hennepin 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 Sylvan Lake are listed below.
Top-rated places to stay near Sylvan Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Sylvan Lake typically sits around 72°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 73°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 87 field readings (2023–2024) via the EPA Water Quality Portal. See the full Sylvan Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~8 ft est. |
| Public Access | No |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Sylvan Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Sylvan Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.06 m/yr | 2 |
| Phosphorus | ↑ Improving | -80.1 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -36 µg/L/yr | 2 |
EPA Impairment Status
Sylvan 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 MN27-0171-00 · Official waterbody report
County Ranking
Ranked #74 of 81 lakes in Hennepin County
Nearby Lakes With Higher Grades
Sylvan 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.
See full comparison →Nearby Lakes in Hennepin County
Frequently asked questions about Sylvan Lake
What is the water quality grade for Sylvan Lake?
- Sylvan Lake in Hennepin County, Minnesota has a water quality grade of F (Algae-prone). Water clarity: 1.2 ft visibility. Phosphorus: 296.6 µg/L. Chlorophyll-a (algae): 84.6 µg/L.
Is Sylvan 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. Sylvan Lake has a water quality grade of F (Algae-prone). Algae concentration (chlorophyll-a) is 84.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Sylvan Lake?
- Sylvan Lake typically sits around 72°F at the surface in August, from 87 EPA Water Quality Portal field readings (2023–2024). That is a typical value for the month, not a live reading.
How deep is Sylvan Lake?
- No published bathymetric survey covers Sylvan Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 8 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Sylvan Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Hennepin County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Crow River Watershed, ranked by water quality
Very high nutrients, dense algae, poor clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Sylvan Lake
Other Grade F Lakes in Minnesota
Hypereutrophic Lakes in Minnesota
Where this data comes from
65 measurements from 1 monitoring station, 2023–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA65 samples · 2023–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 4500 N C ~ Persufate Method for Total Nitrogen
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder