Timber Lake
Lake County, IllinoisView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Noxious aquatic plants
- 47 ft max depth
- Public access
- Limited data
Timber Lake in Lake County, Illinois is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.6 ft visibility.
- Clarity
- 10.6 ft
- Max depth
- ~47 ft est.
- Public access
- Yes
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Stays near Timber Lake
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Watch Timber Lake’s letter
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Why Timber Lake has no grade
Timber Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Timber Lake is Not Rated — not an F. Its 10.6-foot median from 2 readings collected 2020 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by Illinois EPA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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. Grade methodology: LakeQuality methodology.
What Timber Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.6 ft of visibility
Swimming Safety
Not ratedLimited data
The letter is 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.
Water quality measurements for Timber Lake
These readings exist but are not enough for an A–F grade — see why.
Good clarity, visible to about 10.6 ft. TSI 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~47 ft est. |
| Average Depth | ~9 ft est. |
| Public Access | Yes |
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
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.
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RTZQ · Official waterbody report · Matched by proximity (0.04 km)
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.
Graded lakes near Timber Lake
Timber Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Lake County
Frequently asked questions about Timber Lake
Where is Timber Lake?
- Timber Lake is a lake in Lake County, Illinois. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Timber Lake?
- Timber Lake in Lake County, Illinois is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.6 ft visibility.
Is Timber Lake safe to swim in?
- The letter is 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.
Explore Timber Lake across LakeQuality
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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)
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)