Poss Lake
DuPage County, IllinoisView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- #1 of 1 in the county
- Limited data
Poss Lake in DuPage County, Illinois has a water quality grade of D (Nutrient-rich). Water clarity: 1.2 ft visibility. Phosphorus: 66 µg/L. Chlorophyll-a (algae): 29.5 µg/L.
- Clarity
- 1.2 ft
- Typical in September
- 70°F
- Type
- Eutrophic
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 grade measures nutrients and algae, not lodging — cabins and rentals around Poss Lake are listed below.
Top-rated places to stay near Poss Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Poss Lake is a productive, nutrient-rich eutrophic lake in DuPage County, Illinois. Water quality is graded D based on 2 sampling years through 2021.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2021-09-22. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 1.2 ft of visibility. Phosphorus 66 µg/L. Chlorophyll-a 29.5 µg/L. TSI 68. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.2 ft | Not graded |
| Phosphorus | 66 µg/L | Poor |
| Chlorophyll-a (Algae) | 29.5 µg/L | Poor |
| Trophic State Index (TSI) | 68 | Eutrophic |
High nutrients, frequent algae, reduced clarity
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.
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 →
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.
County Ranking
Ranked #1 of 1 lakes in DuPage County
Nearby Lakes in DuPage County
Frequently asked questions about Poss Lake
Where is Poss Lake?
- Poss Lake is a lake in DuPage County, Illinois. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Poss Lake?
- Poss Lake in DuPage County, Illinois has a water quality grade of D (Nutrient-rich). Water clarity: 1.2 ft visibility. Phosphorus: 66 µg/L. Chlorophyll-a (algae): 29.5 µg/L.
Is Poss Lake safe to swim in?
- The D is nutrients and algae, 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.
Explore Poss Lake across LakeQuality
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Other Grade D Lakes in Illinois
Eutrophic Lakes in Illinois
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)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)