Lake · Cook County · IL
Is South Pool safe to swim?
Satellite data here is inconclusive; check local advisories before swimming.
Updated August 20, 2026 · EPA CyAN satellite
No bacteria advisory or sampling for this water.
Satellite imagery hints at possible blue-green algae, but this read is low-confidence (few clear pixels or an aging image) and is not confirmed by a water sample. Avoid scummy or discolored water and check your state or county health department.
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Conditions at South Pool are borderline right now.
Get a push the moment it tips into an advisory, and again the day it clears.
What's in the water at South Pool right now
As of August 20, 2026, South Pool in Cook County, Illinois carries a swim caution. EPA's CyAN satellite showed a possible blue-green algae signal here (July 21, 2026), but the read is low-confidence and is not confirmed by a water sample. Modeled rainfall over the past week was about 0.2 in (Open-Meteo, a gridded estimate that can differ from a local gauge), which can wash bacteria and nutrients into the water.
Blue-green algae at South Pool
South Pool is a lake in Cook County, Illinois covering about 0.7 sq mi, the 52nd-largest of the 68 lakes SwimZone monitors in Illinois. EPA's CyAN satellite showed a possible blue-green algae signal here (July 21, 2026), but the read is low-confidence and is not confirmed by a water sample.
Blue-green algae (cyanobacteria) blooms are most common from midsummer into early fall, when the water is warm, calm, and rich in nutrients from runoff. They can produce toxins that make people sick and can be rapidly fatal to dogs, so skip water that looks green, scummy, or like spilled paint, and keep children and pets out of it.
Bloom history at South Pool
From EPA CyAN's satellite archive
Each bar is that summer's peak EPA CyAN satellite estimate (log scale); the red cap is the part above the bloom-level threshold. Satellite estimates, not water samples or posted advisories.
Over 6 summers of EPA CyAN satellite imagery since 2020, South Pool has shown a satellite-estimated bloom-level signal in 6 of them, most recently in August 2025. It shows a bloom-level signal most summers. Its highest satellite estimate was about 1,600,000 cells/mL in September 2024. These are satellite estimates, not water samples or posted advisories; check your state or county health department for official status.
When to swim at South Pool
It is currently peak season for blue-green algae, when warm, calm water lets blooms form fastest. This lake has bloomed in most monitored summers (6 of 6), historically peaking around September. Early summer, before the water fully warms, has generally been the safer window here; check the current read before you go either way.
Frequently asked: swimming in South Pool
- Is it safe to swim in South Pool right now?
- South Pool carries a swim caution today. EPA's CyAN satellite showed a possible blue-green algae signal here (July 21, 2026), but the read is low-confidence and is not confirmed by a water sample. Conditions can change quickly with wind, heat, and rain, so check the posted signs and look at the water before you get in.
- Does South Pool have blue-green algae (cyanobacteria)?
- Unclear. EPA's CyAN satellite showed a possible blue-green algae signal at South Pool on July 21, 2026, but the read is low-confidence and is not confirmed by a water sample. Avoid any scummy or discolored water and check your state or county health department.
- Can dogs swim in South Pool?
- Be careful. The satellite signal at South Pool is low-confidence and unconfirmed, but dogs are much more vulnerable to blue-green algae than people. Keep them away from any green, scummy, or discolored water and check local advisories.
- How often does South Pool have blue-green algae blooms?
- Over 6 summers of EPA CyAN satellite imagery since 2020, South Pool has shown a satellite-estimated bloom-level signal in 6 of them, most recently in August 2025. It shows a bloom-level signal most summers. Its highest satellite estimate was about 1,600,000 cells/mL in September 2024. These are satellite estimates, not water samples or posted advisories; check your state or county health department for official status.
- How many Illinois lakes and beaches are unsafe for swimming today?
- Today, 0 Illinois waters are above a safe-contact threshold and 54 more warrant caution, out of 130 monitored waters SwimZone tracks in the state.
- How is South Pool's water quality measured?
- SwimZone builds this read from EPA CyAN satellite imagery for blue-green algae, official beach and fecal-bacteria advisories where a program monitors South Pool, and a recent-rainfall overlay, all refreshed daily. It was last updated August 20, 2026.
Before you swim: the basics
Swim spots near South Pool
All Illinois →All 6 monitored waters nearest South Pool are clear today.
| Water | Distance | Today | Algae read | Sampled |
|---|---|---|---|---|
| Glencoe Park BeachBeach · Cook County | 16 mi | No advisory | Not monitored | Aug 20 |
| Winnetka Lloyd Park BeachBeach · Cook County | 16 mi | No advisory | Not monitored | Aug 20 |
| Winnetka Maple Park BeachBeach · Cook County | 16 mi | No advisory | Not monitored | Aug 20 |
| Winnetka Tower BeachBeach · Cook County | 16 mi | No advisory | Not monitored | Aug 20 |
| Highland Park Rosewood BeachBeach · Lake County | 16 mi | No advisory | Not monitored | Aug 20 |
| Winnetka Elder Park BeachBeach · Cook County | 16 mi | No advisory | Not monitored | Aug 20 |