Marie Lake
Lake County, IllinoisView mapDirections
Nutrients and algae run well above the regional average.
↓ down from D at the last regrade
- Hypereutrophic
- Impaired · Mercury
- #14 of 19 in the county
- 49 ft max depth
- Limited data
Marie Lake in Lake County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 2.7 ft visibility. Phosphorus: 76 µg/L. Chlorophyll-a (algae): 55 µg/L.
- Clarity
- 2.7 ft
- Typical in August
- 74°F
- Max depth
- ~49 ft est.
- Type
- Hypereutrophic
- Phosphorus
- 76 µg/L
- Chlorophyll-a
- 55 µg/L
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Stays near Marie Lake
Compare lakeside cabins, hotels, and vacation rentals near Marie Lake in Lake County, Illinois — 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 Marie Lake are listed below.
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Marie Lake is a highly nutrient-loaded hypereutrophic lake in Lake County, Illinois with an estimated average depth of about 49 feet. Water quality is graded F based on 2 sampling years through 2022. Public access is available with 1 public boat landing. Compared to the 18 other monitored lakes in Lake County, Marie Lake ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-10-25. Grade methodology: LakeQuality methodology.
What Marie Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
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.
The F is nutrients and algae, not a swimming clearance. Marie Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 2.7 ft of visibility. Phosphorus 76 µg/L. Chlorophyll-a 55 µg/L. TSI 66. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.7 ft | Not graded |
| Phosphorus | 76 µg/L | Poor |
| Chlorophyll-a (Algae) | 55 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Marie Lake typically sits around 74°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 81°F) and coldest in Oct (about 58°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 244 field readings (2012–2022) via the EPA Water Quality Portal. See the full Marie Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~49 ft est. |
| Average Depth | ~10 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Illinois has not published bathymetry for Marie 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.
Recreation & Access
- Chain O' LakesSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Marie Lake
Reservoir Info (USACE NID)
Marie Lake is a man-made reservoir impounded by the Coopers Farm Sediment Storage Dam, built primarily for debris control on the LAKE MARIE - OFFSTREAM; earth-type dam, 13 ft tall and 2,500 ft long.
- Normal storage
- 0 ac-ft
- Max storage
- 6 ac-ft
- Drainage area
- 0.1 sq mi
- Hazard class
- High
- Owner
- ILLINOIS DEPARTMENT OF NATURAL RESOURCES
Source: USACE National Inventory of Dams, NID ID IL55139 · Operator website · Matched by proximity (0.96 km)
EPA Impairment Status
Marie 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 IL_RTR · Official waterbody report
County Ranking
Ranked #14 of 19 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Marie Lake
Where is Marie Lake?
- Marie Lake is a lake in Lake County, Illinois. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Marie Lake?
- Marie Lake in Lake County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 2.7 ft visibility. Phosphorus: 76 µg/L. Chlorophyll-a (algae): 55 µg/L.
Is Marie Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Marie Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pCBs. Check local advisories before you swim.
What is the water temperature of Marie Lake?
- Marie Lake typically sits around 74°F at the surface in August, from 244 EPA Water Quality Portal field readings (2012–2022). That is a typical value for the month, not a live reading.
How deep is Marie Lake?
- No published bathymetric survey covers Marie Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 49 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Marie Lake?
- Marie Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Chain O' Lakes.
Explore Marie Lake across LakeQuality
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
Very high nutrients, dense algae, poor clarity
Illinois's cleanest and most-polluted lakes, ranked
More Illinois Lake Rankings
Other Grade F Lakes in Illinois
Hypereutrophic Lakes in Illinois
Where this data comes from
22 measurements from 2 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX22 samples · 2022
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
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)
Named boat-access points from the USGS National Boat Ramps inventory