Poss Lake
DuPage County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Poss Lake. Here is what has been measured.
- Eutrophic
- Limited data
Poss Lake in DuPage County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 66 µg/L. Chlorophyll-a (algae): 29.5 µg/L.
Poss Lake is a productive, nutrient-rich eutrophic lake in DuPage County, Illinois.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2021-09-22. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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 Poss 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 Poss Lake
These are the measurements Illinois EPA publishes for Poss 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 1.2 ft of visibility. Phosphorus 66 µg/L. Chlorophyll-a 29.5 µg/L. TSI 68.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 66µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 29.5µg/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. | 68 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Poss Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Poss Lake typically sits around 70°F at the surface in September. Summer average is about 69°F. Usually warmest in Jul (about 73°F) and coldest in May (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 (73°F).
Typical surface water temperature by month, from 17 field readings (2021–2021) via the EPA Water Quality Portal. See the full Poss Lake water temperature breakdown →
Stays via Stay22
Stays near Poss Lake
Compare lakeside cabins, hotels, and vacation rentals near Poss Lake in DuPage 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 Poss Lake are listed below.
Top-rated places to stay near Poss Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Illinois’s top lakes →
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Fishing Poss Lake
Regulated Pollution Sources Nearby
13 EPA-permitted facilities operate within about 5 miles of Poss Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 6 facilities have a reported Clean Water Act violation in the past three years.
- Batavia Wwtf, City OfBatavia · 4.1 mi away · NPDES IL0022543MajorRecent violation
- Heartland Recycling - Aurora Ccdd LlcAurora · 3.2 mi away · NPDES IL0071820Recent violation
- Dart Container CorporationNorth Aurora · 3.8 mi away · NPDES IL0051381Recent violation
- Mooseheart-Child City And School-StpMooseheart · 3.8 mi away · NPDES IL0027260Recent violation
- FermilabBatavia · 4.1 mi away · NPDES IL0026123Recent violation
- Phillips Park Family Aquatics CenterAurora · 5 mi away · NPDES IL0075035Recent violation
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 DuPage County
Frequently asked questions about Poss Lake
Where is Poss Lake?
- Poss Lake is a lake in DuPage County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Poss Lake?
- Poss Lake in DuPage County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.2 ft visibility. Phosphorus: 66 µg/L. Chlorophyll-a (algae): 29.5 µg/L.
Is Poss 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 Poss Lake?
- Poss Lake typically sits around 70°F at the surface in September, from 17 EPA Water Quality Portal field readings (2021–2021). That is a typical value for the month, not a live reading.
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Where this data comes from
16 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX16 samples · 2021
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)