Greenfield Lake
Greene County, Illinois52 acresView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #1 of 1 in the county
- 24 ft max depth
- Public access
- Limited data
Greenfield Lake in Greene County, Illinois has a water quality grade of D (Nutrient-rich). Phosphorus: 85.5 µg/L. Chlorophyll-a (algae): 30 µg/L. Surface area: 52 acres.
- Typical in September
- 78°F
- Max depth
- ~24 ft est.
- Area
- 52 acres
- Type
- Eutrophic
- Public access
- Yes
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Stays near Greenfield Lake
Compare lakeside cabins, hotels, and vacation rentals near Greenfield Lake in Greene 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 Greenfield Lake are listed below.
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Greenfield Lake is a 52-acre productive, nutrient-rich eutrophic lake in Greene County, Illinois with an estimated average depth of about 24 feet. Water quality is graded D based on 2 sampling years through 2021. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2021-10-19. Grade methodology: LakeQuality methodology.
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 D is nutrients and algae, not a swimming clearance. Greenfield Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pesticides. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
No clarity data. Phosphorus 85.5 µg/L. Chlorophyll-a 30 µg/L. TSI 66. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 85.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 30 µg/L | Poor |
| Trophic State Index (TSI) | 66 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Greenfield Lake typically sits around 78°F at the surface in September. Summer average is about 78°F. Usually warmest in Jul (about 83°F) and coldest in Apr (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 176 field readings (2014–2021) via the EPA Water Quality Portal. See the full Greenfield Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~24 ft est. |
| Average Depth | ~6 ft est. |
| Surface Area | 52 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Illinois has not published bathymetry for Greenfield 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 Greenfield Lake
Reservoir Info (USACE NID)
Greenfield Lake is a man-made reservoir impounded by the Greenfield City Dam (completed 1959), built primarily for water supply on the TRIB RUBICON CREEK; earth-type dam, 33 ft tall and 650 ft long.
- Surface area
- 52 ac
- Normal storage
- 564 ac-ft
- Max storage
- 899 ac-ft
- Drainage area
- 1.1 sq mi
- Hazard class
- Significant
- Owner
- CITY OF GREENFIELD
Source: USACE National Inventory of Dams, NID ID IL00761 · Operator website · Matched by proximity (0.31 km)
EPA Impairment Status
Greenfield 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_RDZF · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Greenfield Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Greenfield Stp, City OfGreenfield · 0.3 mi away · NPDES IL0029076Recent 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.
County Ranking
Ranked #1 of 1 lakes in Greene County
Nearby Lakes in Greene County
Frequently asked questions about Greenfield Lake
Where is Greenfield Lake?
- Greenfield Lake is a lake in Greene County, Illinois. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Greenfield Lake?
- Greenfield Lake in Greene County, Illinois has a water quality grade of D (Nutrient-rich). Phosphorus: 85.5 µg/L. Chlorophyll-a (algae): 30 µg/L. Surface area: 52 acres.
Is Greenfield Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Greenfield Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), pesticides. Check local advisories before you swim.
What is the water temperature of Greenfield Lake?
- Greenfield Lake typically sits around 78°F at the surface in September, from 176 EPA Water Quality Portal field readings (2014–2021). That is a typical value for the month, not a live reading.
How deep is Greenfield Lake?
- No published bathymetric survey covers Greenfield Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 52 acres.
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Where this data comes from
40 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX40 samples · 2021
Analytical methods
- 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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)