Lake County, Illinois · Water Quality Report Card
Valley Lake
Valley Lake in Lake County, Illinois has a water quality grade of F (Very Poor). Chlorophyll-a (algae): 50.7 µg/L.
- Type
- Hypereutrophic
Valley Lake is a highly nutrient-loaded hypereutrophic lake in Lake County, Illinois. Water quality is graded F based on 1 sampling years through 2020. Compared to the 18 other monitored lakes in Lake County, Valley Lake ranks #17 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2020-09-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F (Very Poor)
No clarity data. Chlorophyll-a: 50.7 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 50.7 µg/L | Poor |
| Trophic State Index (TSI) | 69 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Valley Lake
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Fishing Valley Lake
Location
County Ranking
Ranked #17 of 19 lakes in Lake County
Nearby Lakes in Lake County
Explore Valley Lake across LakeGrade
Species activity outlook by water temperature and season
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Where to stay at Illinois's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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More records, surveys & data sources
EPA Impairment Status
Valley Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IL_RGZM · Official waterbody report
Where this data comes from
8 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX8 samples · 2020
Analytical methods
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2020-09-23
Monitoring stations: 1