Salem Lake
Marion County, Illinois78 acresView mapDirections
Illinois EPA publishes the water-quality measurements for Salem Lake. Here is what has been measured.
- Hypereutrophic
- 46 ft max depth
- Public access
Salem Lake in Marion County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1 ft visibility. Phosphorus: 234 µg/L. Chlorophyll-a (algae): 77.5 µg/L. Surface area: 78 acres.
Salem Lake is a 78-acre highly nutrient-loaded hypereutrophic lake in Marion County, Illinois with an estimated average depth of about 46 feet. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 5 other monitored lakes in Marion County, Salem Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-10-19. Methodology: how these readings are compared.
What Salem Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyAlgae risk
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 Salem 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 Salem Lake
These are the measurements Illinois EPA publishes for Salem 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 1 ft of visibility. Phosphorus 234 µg/L. Chlorophyll-a 77.5 µg/L. TSI 78.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 234µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 77.5µg/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. | 78 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Salem Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Salem Lake typically sits around 58°F at the surface in October. Summer average is about 81°F. Usually warmest in Jul (about 82°F) and coldest in Oct (about 58°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (58°F) to its warmest (82°F).
Typical surface water temperature by month, from 234 field readings (2010–2022) via the EPA Water Quality Portal. See the full Salem Lake water temperature breakdown →
Lake Details
Max depth
~46 ft est.
Surface area
78 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 Salem Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.7 mi
HydroLAKES / HydroSHEDS
Elevation
548 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
- Salem ReservoirPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Salem Lake
Compare lakeside cabins, hotels, and vacation rentals near Salem Lake in Marion 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 Salem Lake are listed below.
Top-rated places to stay near Salem Lake
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 whole trip? See where to stay at Illinois’s top lakes →
Follow Salem Lake’s readings
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Fishing Salem Lake
Water quality readings over time
2 seasons of samples on record (2020–2022). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Improving-14 µg/L/yr2 years
Chlorophyll-a
Stable+1.05 µg/L/yr2 years
Reservoir Info (USACE NID)
Salem Lake is a man-made reservoir impounded by the Salem Reservoir Dam (completed 1912), built primarily for recreation on the TOWN CREEK; earth-type dam, 21 ft tall and 775 ft long.
- Surface area
- 78 ac
- Normal storage
- 388 ac-ft
- Max storage
- 900 ac-ft
- Drainage area
- 3.9 sq mi
- Hazard class
- High
- Owner
- CITY OF SALEM
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID IL00245 · Operator website
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Salem Lake 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.
- Salem Stp, City OfSalem · 2.1 mi away · NPDES IL0023264MajorRecent violation
- Union Pacific Railroad-SalemSalem · 1.7 mi away · NPDES IL0000361
- Salem Municipal Landfill #2Salem · 2 mi away · NPDES IL0075621
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 Marion County
Frequently asked questions about Salem Lake
Where is Salem Lake?
- Salem Lake is a lake in Marion County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Salem Lake?
- Salem Lake in Marion County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1 ft visibility. Phosphorus: 234 µg/L. Chlorophyll-a (algae): 77.5 µg/L. Surface area: 78 acres.
Is Salem Lake 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 Salem Lake?
- Salem Lake typically sits around 58°F at the surface in October, from 234 EPA Water Quality Portal field readings (2010–2022). That is a typical value for the month, not a live reading.
How deep is Salem Lake?
- No published bathymetric survey covers Salem Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 46 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 78 acres.
Are there boat ramps on Salem Lake?
- Salem Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Salem Reservoir. Public access is listed as yes.
Can I fish at Salem Lake?
- Salem Lake has 1 documented boat landing 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 Salem Lake across LakeQuality
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Where this data comes from
102 measurements from 3 monitoring stations, 2020–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX102 samples · 2020–2022
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
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