Round Lake is a 242-acre mesotrophic lake in Lake County, Illinois. Water quality is graded B based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 15 other monitored lakes in Lake County, Round Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-10-12. Grade methodology: LakeGrade methodology.
Watch Round Lake water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Moderate clarity, visible to about 7.4 ft. Phosphorus level: 19.5 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.4 ft | C |
| Phosphorus | 19.5 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 242 acres |
| Public Access | Yes |
Where to stay near Round Lake
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Fishing Round Lake
Recreation & Access
Water Temperature
Round Lake averages about 72°F at the surface in summer, usually warmest in Jul (about 75°F) and coldest in May (about 59°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 380 field readings (2012–2022) via the EPA Water Quality Portal. See the full Round Lake water temperature breakdown →
Location
County Ranking
Ranked #4 of 16 lakes in Lake County
Nearby Lakes in Lake County
Explore Round Lake across LakeGrade
Species activity outlook by water temperature and season
Top lakes and where to stay in the Chain O'Lakes area
Where to stay at Illinois's top lakes, each with its grade
Moderate nutrients, good water quality
Illinois's cleanest and most-polluted lakes, ranked
More Illinois Lake Rankings
Other Grade B Lakes in Illinois
Mesotrophic Lakes in Illinois
More records, surveys & data sources
Reservoir Info (USACE NID)
Round Lake is a man-made reservoir impounded by the Round Lake Dam (completed 1945), built primarily for recreation on the TRIB SQUAW CREEK; earth-type dam, 9 ft tall and 140 ft long.
- Surface area
- 242 ac
- Normal storage
- 976 ac-ft
- Max storage
- 1,484 ac-ft
- Drainage area
- 2.5 sq mi
- Hazard class
- Significant
- Owner
- VILLAGE OF ROUND LAKE BEACH
Source: USACE National Inventory of Dams, NID ID IL00593 · Operator website
EPA Impairment Status
Round Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IL_RTZP · Official waterbody report · Matched by proximity (1.29 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Round Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Fonks Home Center, Inc. - Hickory HavenKansasville · 3.4 mi away · NPDES WI0030660Recent violation
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2022-10-12
Monitoring stations: 3