Olney East Fork Lake
Richland County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Olney East Fork Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- 47 ft max depth
- Public access
- Limited data
Olney East Fork Lake in Richland County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 3.2 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 29.6 µg/L.
Olney East Fork Lake is a productive, nutrient-rich eutrophic lake in Richland County, Illinois with an estimated average depth of about 47 feet. Limited fish-species data available. Public access is available. Compared to the 2 other monitored lakes in Richland County, Olney East Fork Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-10-31. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Olney East Fork Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Olney East Fork Lake is safe to swim in today is a call for the Illinois Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Olney East Fork Lake
These are the measurements Illinois EPA publishes for Olney East Fork Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 3.2 ft of visibility. Phosphorus 37 µg/L. Chlorophyll-a 29.6 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 37µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 29.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Olney East Fork Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Olney East Fork Lake typically sits around 61°F at the surface in October. Summer average is about 80°F. Usually warmest in Jul (about 84°F) and coldest in Oct (about 61°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (61°F) to its warmest (84°F).
Typical surface water temperature by month, from 181 field readings (2012–2022) via the EPA Water Quality Portal. See the full Olney East Fork Lake water temperature breakdown →
Lake Details
Max depth
~47 ft est.
Public access
Yes
Listed by Illinois EPA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Illinois has not published bathymetry for Olney East Fork Lake.
Lake Size & Watershed
Watershed (drainage) area
18 sq mi
HydroLAKES / HydroSHEDS
Surface area
635 acres
HydroLAKES / HydroSHEDS
Shoreline
12.9 mi
HydroLAKES / HydroSHEDS
Elevation
472 ft
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.
Stays via Stay22
Stays near Olney East Fork Lake
Compare lakeside cabins, hotels, and vacation rentals near Olney East Fork Lake in Richland 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Olney East Fork Lake are listed below.
Top-rated places to stay near Olney East Fork Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Fishing Olney East Fork Lake
EPA Impairment Status
Olney East Fork Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption, Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RCC · Official waterbody report
Nearby Lakes in Richland County
Frequently asked questions about Olney East Fork Lake
Where is Olney East Fork Lake?
- Olney East Fork Lake is a lake in Richland County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Olney East Fork Lake?
- Olney East Fork Lake in Richland County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 3.2 ft visibility. Phosphorus: 37 µg/L. Chlorophyll-a (algae): 29.6 µg/L.
Is Olney East Fork Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Olney East Fork Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Olney East Fork Lake?
- Olney East Fork Lake typically sits around 61°F at the surface in October, from 181 EPA Water Quality Portal field readings (2012–2022). That is a typical value for the month, not a live reading.
How deep is Olney East Fork Lake?
- No published bathymetric survey covers Olney East Fork Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 47 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Olney East Fork Lake?
- Public access to Olney East Fork Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Illinois's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
40 measurements from 3 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX40 samples · 2022
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (3)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)