Timber Lake
Lake County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Timber Lake. Here is what has been measured.
- Impaired · Noxious aquatic plants
- 47 ft max depth
- Public access
- Limited data
Timber Lake in Lake County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 10.6 ft visibility.
Timber Lake is a lake in Lake County, Illinois with an estimated average depth of about 47 feet. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2020-07-20. Methodology: how these readings are compared.
What Timber Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.6 ft of visibility
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Timber Lake is listed impaired under Clean Water Act §303(d) (IR 5) for noxious aquatic plants, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
Whether Timber 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 Timber Lake
These are the measurements Illinois EPA publishes for Timber Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10.6 ft. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Timber Lake
Answers come straight from the public measurements and survey records on this page.
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 Timber Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
30 acres
HydroLAKES / HydroSHEDS
Shoreline
1 mi
HydroLAKES / HydroSHEDS
Elevation
787 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.
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Stays near Timber Lake
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Fishing Timber Lake
Reservoir Info (USACE NID)
Timber Lake is a man-made reservoir impounded by the Timber Lake Dam (completed 1949), built primarily for recreation on the TRIB TOWER LAKE; earth-type dam, 20 ft tall and 320 ft long.
- Normal storage
- 240 ac-ft
- Max storage
- 292 ac-ft
- Hazard class
- Low
- Owner
- MICHAEL GRAFF
Source: USACE National Inventory of Dams, NID ID IL00632 · Operator website
EPA Impairment Status
Timber 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: Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RTZQ · Official waterbody report
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Timber Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 4 facilities have a reported Clean Water Act violation in the past three years.
- Wauconda WwtfWauconda · 1.7 mi away · NPDES IL0020109MajorRecent violation
- Mount Saint Joseph Home StpLake Zurich · 1.1 mi away · NPDES IL0027286Recent violation
- North Barrington Elementary School StpBarrington · 2 mi away · NPDES IL0024716Recent violation
- Lake Barrington Homeowners Association StpLake Barrington · 2.9 mi away · NPDES IL0045110Recent violation
- Cm Products IncLake Zurich · 4.3 mi away · NPDES IL0066311
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 Lake County
Frequently asked questions about Timber Lake
Where is Timber Lake?
- Timber Lake is a lake in Lake County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Timber Lake?
- Timber Lake in Lake County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 10.6 ft visibility.
Is Timber Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Timber Lake is listed impaired under Clean Water Act §303(d) (IR 5) for noxious aquatic plants, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
How deep is Timber Lake?
- No published bathymetric survey covers Timber 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 Timber Lake?
- Public access to Timber 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
2 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS2 samples · 2020
Monitoring station identifiers (1)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)