Fairfield Lake
Wayne County, Illinois18 acresView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #3 of 3 in the county
Fairfield Lake in Wayne County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 1.3 ft visibility. Phosphorus: 148 µg/L. Chlorophyll-a (algae): 35.4 µg/L. Surface area: 18 acres.
- Clarity
- 1.3 ft
- Typical in August
- 80°F
- Area
- 18 acres
- Type
- Hypereutrophic
- Phosphorus
- 148 µg/L
- Chlorophyll-a
- 35.4 µg/L
- Trend
- ↑ Improving
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Stays near Fairfield Lake
Compare lakeside cabins, hotels, and vacation rentals near Fairfield Lake in Wayne 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 Fairfield Lake are listed below.
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Watch Fairfield Lake’s letter
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Fairfield Lake is a 18-acre highly nutrient-loaded hypereutrophic lake in Wayne County, Illinois. Water quality is graded F based on 2 sampling years through 2022. Overall water quality is improving over recent sampling years. Compared to the 2 other monitored lakes in Wayne County, Fairfield Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-10-24. Grade methodology: LakeQuality methodology.
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.
The F is nutrients and algae, not a swimming clearance. Fairfield Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 1.3 ft of visibility. Phosphorus 148 µg/L. Chlorophyll-a 35.4 µg/L. TSI 72. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | Not graded |
| Phosphorus | 148 µg/L | Poor |
| Chlorophyll-a (Algae) | 35.4 µg/L | Poor |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Fairfield Lake typically sits around 80°F at the surface in August. Summer average is about 82°F. Usually warmest in Jul (about 86°F) and coldest in Nov (about 59°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 91 field readings (2012–2022) via the EPA Water Quality Portal. See the full Fairfield Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 18 acres |
No bathymetric survey has been published for Fairfield Lake, so its depth is not documented here.
Fishing Fairfield Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -2 m/yr | 2 |
| Phosphorus | ↑ Improving | -18 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -7.9 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Fairfield Lake is a man-made reservoir impounded by the Fairfield Side Channel Reservoir Dam (completed 1979), built primarily for water supply on the TRIB LITTLE WABASH R; earth-type dam, 16 ft tall and 1,850 ft long.
- Surface area
- 18 ac
- Normal storage
- 274.66 ac-ft
- Max storage
- 328.66 ac-ft
- Drainage area
- 0.03 sq mi
- Hazard class
- Low
- Owner
- CITY OF FAIRFIELD
Source: USACE National Inventory of Dams, NID ID IL50585 · Operator website · Matched by proximity (0.21 km)
EPA Impairment Status
Fairfield 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_RCZJ · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Fairfield Lake under Clean Water Act (NPDES) discharge permits.
- Fairfield Wtp, City OfFairfield · 0.3 mi away · NPDES IL0046248
- Fairfield Water Treatment Plant, City OfFairfield · 4.1 mi away · NPDES IL0079375
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 #3 of 3 lakes in Wayne County
Nearby Lakes in Wayne County
Frequently asked questions about Fairfield Lake
Where is Fairfield Lake?
- Fairfield Lake is a lake in Wayne County, Illinois. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Fairfield Lake?
- Fairfield Lake in Wayne County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 1.3 ft visibility. Phosphorus: 148 µg/L. Chlorophyll-a (algae): 35.4 µg/L. Surface area: 18 acres.
Is Fairfield Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Fairfield Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Fairfield Lake?
- Fairfield Lake typically sits around 80°F at the surface in August, from 91 EPA Water Quality Portal field readings (2012–2022). That is a typical value for the month, not a live reading.
Explore Fairfield Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Where this data comes from
38 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX38 samples · 2021–2022
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
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)