Lake County lake statistics at a glance
Lake County is shaped by water in a very literal way: roughly 20% of the county is covered by surface water made up of streams, lakes, wetlands, and floodplains (Why We Flood | Lake County, IL). That single figure frames the rest of the story, because the county’s lake system is not just a list of isolated water bodies, but a connected network of watersheds, river systems, wetlands, and long-running monitoring work.
Table of contents
- Fast facts
- How Lake County’s lake network fits together
- What the lake studies cover
- Comparing key lake reports
- Water clarity and phosphorus snapshots
- Vegetation and habitat signals
- What the numbers suggest
Fast facts
Big number: Lake County has 4 major watersheds and 3 major river systems that run wholly or partly through the county (Why We Flood | Lake County, IL). Those watersheds drain into about 545 miles of streams and then into 170 lakes (Why We Flood | Lake County, IL).
Wetland and floodplain scale: the county contains 8,750 acres of wetlands and 55,434 acres of floodplain (Why We Flood | Lake County, IL). That combination matters because lake conditions are influenced by what happens outside the shoreline as much as by what happens on the water.
Monitoring scale: since 2000, the Lakes Management Unit has studied 176 different lakes in Lake County (Lake Reports | Lake County, IL). That means the county’s lake statistics are not a single snapshot; they are part of a long-running monitoring system that tracks physical, chemical, and biological conditions over time.
At a glance
- Surface-water footprint: about 20% of the county (Why We Flood | Lake County, IL)
- Major watersheds: 4 (Why We Flood | Lake County, IL)
- Major river systems: 3 (Why We Flood | Lake County, IL)
- Stream network length: about 545 miles (Why We Flood | Lake County, IL)
- Lakes connected to the system: 170 (Why We Flood | Lake County, IL)
- Wetlands: 8,750 acres (Why We Flood | Lake County, IL)
- Floodplain: 55,434 acres (Why We Flood | Lake County, IL)
- Lakes studied since 2000: 176 (Lake Reports | Lake County, IL)
How Lake County’s lake network fits together
The keyword here is not just “lake,” but system. Lake County’s watersheds drain through a large stream network before reaching the lakes, and the county’s surface water footprint includes streams, wetlands, and floodplains as well as open water (Why We Flood | Lake County, IL). That structure helps explain why lake conditions can vary so much from one basin to another.
A useful way to think about the county is as a connected drainage landscape:
- Watersheds collect runoff from land.
- River systems move that water through the county.
- Streams distribute flow across the network.
- Lakes receive water, sediment, nutrients, and plant growth signals from the broader basin.
- Wetlands and floodplains shape storage, filtration, and peak-flow behavior.
The raw numbers support that view. With 545 miles of streams feeding 170 lakes, Lake County’s lake statistics are tied to a dense surface-water network rather than a few isolated basins (Why We Flood | Lake County, IL). The county’s 8,750 acres of wetlands and 55,434 acres of floodplain add another layer of hydrologic complexity (Why We Flood | Lake County, IL).
What the lake studies cover
The county’s long-running lake studies do more than count surface area or depth. Since 2000, the Lakes Management Unit has collected data on:
- temperature
- dissolved oxygen
- phosphorus
- nitrogen
- solids
- pH
- alkalinity
- chloride
- conductivity
- water clarity
- the plant community
- shoreline characteristics
That list matters because it shows the monitoring program is looking at both water quality and habitat structure (Lake Reports | Lake County, IL). In practice, these measurements help connect visible lake conditions, such as clarity and vegetation cover, to less visible drivers like nutrients and conductivity.
Why it matters
The lake reports are useful because they reveal multiple layers of condition at once. A lake can be deep or shallow, clear or turbid, vegetation-rich or vegetation-poor, and still fit into a broader countywide pattern. The strength of the dataset is that it lets you compare all those pieces side by side using the same reporting system.
Comparing key lake reports
Some of the most useful numbers in the dataset come from individual lake reports. Those reports make it easier to compare lake size, shape, depth, clarity, and nutrient signals in one view.
| Lake | Surface area | Shoreline length | Maximum depth | Average depth | Volume | Watershed area | Water clarity | Notable ranking or metric |
|---|---|---|---|---|---|---|---|---|
| Petite Lake | 195.44 acres | 6.36 miles | 19.00 feet | 5.15 feet | 1,251.58 acre-feet | 25,757.51 acres in Wisconsin and Illinois | 2.0 feet in 2014 | 116th out of 158 lakes for average Secchi depth since 2000 (2014 Petite Lake Report) |
| Lake Marie | 595.82 acres | 16.01 miles | 30.00 feet | 16.7 feet | 5,064.87 acre-feet | 23,084.95 acres in Wisconsin and Illinois | 1.9 feet in 2014 | 131st out of 158 lakes for average Secchi depth since 2000 (2014 Lake Marie Report) |
| Channel Lake | not provided | not provided | 39.00 feet | 16.7 feet | 2,881.90 acre-feet | 12,581.67 acres in Wisconsin and Illinois | 2.8 feet in 2014 | 89th out of 158 lakes for average Secchi depth since 2000 (2014 Channel Lake Report) |
| Grass Lake | not provided | 20.87 miles | 6.0 feet | 2.25 feet | 3,652.7 acre-feet | 13,844 acres in Illinois and 600,046 acres in Wisconsin | 0.78 feet in 2014 | TSS of 38.7 mg/L in 2014 (2014 Grass Lake Report) |
| Timber Lake North | 33.3 acres | 1.0 mile | 33.3 feet | 16.5 feet | 547.1 acre-feet | 412.1 acres | 9.22 feet in 2010 | VLMP average Secchi depth in 2010 (2010 Timber Lake North Report) |
| Deer Lake | 49.7 acres | 1.2 miles | 8.9 feet | 5.3 feet | 241.2 acre-feet | 2,293.5 acres | 4.20 feet in 2010 | LCHD average Secchi depth in 2010 (2010 Deer Lake Report) |
| McDonald Woods Lake #2 | 21.2 acres | 1.65 miles | 2.8 feet | 2.0 feet | 27.5 acre-feet | 578.6 acres | 0.5 feet in 2010 | Ranked last out of 153 lakes sampled in Lake County for water clarity (2010 McDonald Woods Lake #2 Report) |
The table shows that Lake County’s lakes vary dramatically in size, depth, and clarity. Petite Lake, Lake Marie, and Channel Lake are all large enough to carry substantial watershed influence, while smaller systems like Timber Lake North and McDonald Woods Lake #2 show how shallow or limited water volume can shape lake conditions (2014 Petite Lake Report; 2014 Lake Marie Report; 2014 Channel Lake Report; 2010 Timber Lake North Report; 2010 McDonald Woods Lake #2 Report).
Water clarity and phosphorus snapshots
Water clarity appears repeatedly in the county reports because it is one of the clearest indicators of lake condition. Several of the supplied lakes show particularly low Secchi depth values, which signals reduced clarity.
Key clarity figures:
- Petite Lake’s average water clarity in 2014 was 2.0 feet (2014 Petite Lake Report)
- Lake Marie’s average water clarity in 2014 was 1.9 feet (2014 Lake Marie Report)
- Channel Lake’s average water clarity in 2014 was 2.8 feet (2014 Channel Lake Report)
- Grass Lake’s average Secchi depth in 2014 was 0.78 feet (2014 Grass Lake Report)
- Timber Lake North’s VLMP average Secchi depth in 2010 was 9.22 feet (2010 Timber Lake North Report)
- Deer Lake’s LCHD average Secchi depth in 2010 was 4.20 feet (2010 Deer Lake Report)
- McDonald Woods Lake #2’s average Secchi depth in 2010 was 0.5 feet (2010 McDonald Woods Lake #2 Report)
A few of the clearer comparison points are especially useful. Channel Lake ranked 89th out of 158 lakes for average Secchi depth since 2000, which places it in the middle of the pack rather than at the extreme low end (2014 Channel Lake Report). Petite Lake ranked 116th out of 158 lakes for average Secchi depth since 2000, while Lake Marie ranked 131st out of 158 lakes for the same measure (2014 Petite Lake Report; 2014 Lake Marie Report). McDonald Woods Lake #2 went even lower, ranking last out of 153 lakes sampled in Lake County for water clarity (2010 McDonald Woods Lake #2 Report).
Fast facts on nutrients and solids
Lake County’s reports also show how clarity connects to nutrient and solids data. A few highlights:
- Lake Marie’s average total phosphorus concentration in 2014 was 0.068 mg/L (2014 Lake Marie Report)
- Lake Marie ranked 116th out of 173 lakes sampled for TP since 2000 (2014 Lake Marie Report)
- Channel Lake’s average total phosphorus concentration in 2014 was 0.068 mg/L (2014 Channel Lake Report)
- Channel Lake ranked 77th out of 173 lakes sampled for TP since 2000 (2014 Channel Lake Report)
- Grass Lake’s average total suspended solids concentration was 38.7 mg/L (2014 Grass Lake Report)
- Grass Lake’s 2014 TSS level was 16.9% lower than the 2002 average of 46.6 mg/L (2014 Grass Lake Report)
- Timber Lake North’s average TSS concentration in 2010 was 2.5 mg/L (2010 Timber Lake North Report)
- Deer Lake’s average TSS concentration in 2010 was 7.8 mg/L (2010 Deer Lake Report)
The dataset does not ask you to infer a single universal trend for every lake. Instead, it shows that Lake County’s lakes can share similar phosphorus values while still diverging sharply on clarity, solids, and vegetation behavior. That is a useful reminder that lake statistics are multi-factor, not one-dimensional.
Vegetation and habitat signals
Aquatic vegetation appears in the county reports as another major layer of lake condition. Here, the numbers are not just about whether plants exist, but about how much of the lake they occupy and how diverse the plant community is.
Channel Lake recorded 25.9% aquatic vegetation colonization of sampled points in 2014 and an average aquatic vegetation cover of 31.19% at sampled points (2014 Channel Lake Report). It also had a floristic quality assessment score of 18.7 and 11 aquatic plant species recorded in 2014 (2014 Channel Lake Report). That makes it one of the richer examples in the dataset for connecting plant structure to lake monitoring.
Lake Marie’s aquatic vegetation cover in 2014 was 27.84%, and it had 4 dominant aquatic plant species (2014 Lake Marie Report). For a lake of its size, that kind of vegetation reporting helps show how plant communities vary by basin rather than simply by lake area.
What the vegetation data adds
Vegetation data helps answer questions that water chemistry alone cannot. For example:
- How much of the lake bottom is colonized by plants?
- How many dominant species shape the habitat?
- Is plant growth concentrated or more evenly distributed?
- Do plant patterns line up with clarity and nutrient measures?
Those questions are especially relevant in a county where 176 different lakes have been studied since 2000 (Lake Reports | Lake County, IL). The point is not to treat one lake as representative of all others, but to use the long record to see how habitat and water quality interact across many settings.
Reading the rankings carefully
Several of the supplied statistics include rankings, and those rankings deserve careful reading. A lower rank in this dataset often signals weaker clarity or poorer status relative to the comparison group, but the exact benchmark changes by report. That means the rank is useful when paired with the raw metric, not as a stand-alone conclusion.
A few examples make that clear:
- Petite Lake was 116th out of 158 for average Secchi depth since 2000, with 2014 clarity at 2.0 feet (2014 Petite Lake Report)
- Lake Marie was 131st out of 158 for average Secchi depth since 2000, with 2014 clarity at 1.9 feet (2014 Lake Marie Report)
- Channel Lake was 89th out of 158 for average Secchi depth since 2000, with 2014 clarity at 2.8 feet (2014 Channel Lake Report)
- Channel Lake ranked 77th out of 173 for TP since 2000, with 2014 TP at 0.068 mg/L (2014 Channel Lake Report)
- McDonald Woods Lake #2 ranked last out of 153 for water clarity, with Secchi depth at 0.5 feet in 2010 (2010 McDonald Woods Lake #2 Report)
That pattern shows why the county’s reporting is so useful. A raw measurement tells you what was observed. A ranking tells you how it compares within the local monitoring set. Used together, they make the lake statistics far more informative.
What the numbers suggest
The strongest pattern in the dataset is scale. Lake County has a large connected water system, and its lake statistics reflect that scale through watersheds, stream miles, wetland acreage, floodplain extent, and a long monitoring history (Why We Flood | Lake County, IL; Lake Reports | Lake County, IL). The second pattern is variation: some lakes are large and deep, some are shallow and highly turbid, and some combine relatively strong depth with middling clarity or nutrient rankings.
A few takeaways stand out from the supplied figures:
- The county’s lake conditions should be read as part of a drainage system, not as isolated lake facts (Why We Flood | Lake County, IL).
- Water clarity is often low enough to matter even where lakes are relatively large or deep, as shown by Lake Marie, Petite Lake, Grass Lake, and McDonald Woods Lake #2 (2014 Lake Marie Report; 2014 Petite Lake Report; 2014 Grass Lake Report; 2010 McDonald Woods Lake #2 Report).
- Nutrient values and solids data help explain why clarity can differ sharply from lake to lake even within the same county monitoring program (2014 Lake Marie Report; 2014 Channel Lake Report; 2014 Grass Lake Report).
- Vegetation metrics add a habitat layer that gives the reports more depth than a basic water-quality summary (2014 Channel Lake Report; 2014 Lake Marie Report).
- The long time span of monitoring since 2000 means county lake statistics are best understood as an evolving record, not a one-off survey (Lake Reports | Lake County, IL).
Lake County’s lake statistics are most useful when you read them together. The watershed counts explain the setting, the lake reports explain the conditions, and the repeated measurements show how much variation exists across the county’s water network.