Lake of Egypt
Williamson County, Illinois2,265 acresView mapDirections
Illinois EPA publishes the water-quality measurements for Lake of Egypt. Here is what has been measured.
- Eutrophic
- 75 ft max depth
- Public access
- Limited data
Lake of Egypt in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 3.2 ft visibility. Phosphorus: 40.5 µg/L. Chlorophyll-a (algae): 22.1 µg/L. Surface area: 2265 acres.
Lake of Egypt is a 2,265-acre productive, nutrient-rich eutrophic lake in Williamson County, Illinois with an estimated average depth of about 75 feet. Limited fish-species data available. Public access is available with 9 public boat landings.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2020-10-26. Methodology: how these readings are compared.
Lake of Egypt covers about 2,300 acres in Williamson County. It has 9 public boat landings, so a lakefront rental is not the only way to get a boat on the water. For a place on the water, look through cabin and lake-house rentals near Lake of Egypt on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Lake of Egypt is good for
From access and monitoring records, not editorial picks.
- Boat launch9 documented ramps
- Big water2,265 acres
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. Check local advisories before you swim.
Whether Lake of Egypt 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 Lake of Egypt
These are the measurements Illinois EPA publishes for Lake of Egypt, 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 40.5 µg/L. Chlorophyll-a 22.1 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 | 40.5µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 22.1µg/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 Lake of Egypt
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Lake of Egypt typically sits around 67°F at the surface in October. Summer average is about 82°F. Usually warmest in Aug (about 85°F) and coldest in Apr (about 60°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (60°F) to its warmest (85°F).
Typical surface water temperature by month, from 217 field readings (2010–2020) via the EPA Water Quality Portal. See the full Lake of Egypt water temperature breakdown →
Lake Details
Max depth
~75 ft est.
Surface area
2,265 acres
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 Lake of Egypt.
Lake Size & Watershed
Watershed (drainage) area
34 sq mi
HydroLAKES / HydroSHEDS
Shoreline
39.3 mi
HydroLAKES / HydroSHEDS
Elevation
502 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.
Recreation & Access
- Lake of EgyptPublic
- Lake of EgyptPublic
- Lake of EgyptPublic
- Lake of EgyptPublic
- Lake of EgyptPublic
- Lake of EgyptPublic
Showing 6 of 9 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Lake of Egypt
Compare lakeside cabins, hotels, and vacation rentals near Lake of Egypt in Williamson 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 Lake of Egypt are listed below.
Top-rated places to stay near Lake of Egypt
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Lake of Egypt → · more Illinois lake trips
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Fishing Lake of Egypt
Reservoir Info (USACE NID)
Lake of Egypt is a man-made reservoir impounded by the Lake of Egypt Dam (completed 1962), built primarily for other on the SOUTH FORK SALINE RIVER; earth-type dam, 55 ft tall and 2,850 ft long.
- Surface area
- 2,265 ac
- Normal storage
- 41,215 ac-ft
- Max storage
- 82,942 ac-ft
- Drainage area
- 33.3 sq mi
- Hazard class
- High
- Owner
- SOUTHERN ILLINOIS POWER COOPERATIVE
All listed purposes: Other;Recreation.
Source: USACE National Inventory of Dams, NID ID IL00015 · Operator website
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Lake of Egypt under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Southern Illinois Power Coopertive - Marion StationMarion · 2.6 mi away · NPDES IL0004316MajorRecent violation
- Lake Egypt Water Dist WtpMarion · 2.4 mi away · NPDES IL0076261
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.
Nearby Lakes in Williamson County
Frequently asked questions about Lake of Egypt
Where is Lake of Egypt?
- Lake of Egypt is a lake in Williamson County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Lake of Egypt?
- Lake of Egypt in Williamson County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 3.2 ft visibility. Phosphorus: 40.5 µg/L. Chlorophyll-a (algae): 22.1 µg/L. Surface area: 2265 acres.
Is Lake of Egypt safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Lake of Egypt?
- Lake of Egypt typically sits around 67°F at the surface in October, from 217 EPA Water Quality Portal field readings (2010–2020). That is a typical value for the month, not a live reading.
How deep is Lake of Egypt?
- No published bathymetric survey covers Lake of Egypt, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 75 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 2265 acres.
Are there boat ramps on Lake of Egypt?
- Lake of Egypt has 9 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lake of Egypt, Lake of Egypt, Lake of Egypt, Lake of Egypt, among others. Public access is listed as yes.
Can I fish at Lake of Egypt?
- Lake of Egypt has 9 documented boat landings in the USGS National Boat Ramps inventory. 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.
Explore Lake of Egypt across LakeQuality
Depth, room, public access, and the state wake-sport rules
15 mi away · 100 ft
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its readings
Illinois's cleanest lakes, ranked on agency measurements
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Where this data comes from
56 measurements from 3 monitoring stations, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX56 samples · 2020
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory