Sparta Northwest Lake is a productive, nutrient-rich eutrophic lake in Randolph County, Illinois. Water quality is graded D based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 2 other monitored lakes in Randolph County, Sparta Northwest Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-10-06. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2.6 ft of visibility. Phosphorus level: 34 µg/L. Trophic State Index: 59.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.6 ft | F |
| Phosphorus | 34 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Sparta Northwest Lake
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Fishing Sparta Northwest Lake
Recreation & Access
Water Temperature
Sparta Northwest Lake averages about 69°F at the surface in summer, usually warmest in Aug (about 72°F) and coldest in Apr (about 54°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 562 field readings (2011–2022) via the EPA Water Quality Portal. See the full Sparta Northwest Lake water temperature breakdown →
Location
County Ranking
Ranked #2 of 3 lakes in Randolph County
Cleaner Lakes Within 30 Miles
Sparta Northwest Lake holds Grade D. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Randolph County
Explore Sparta Northwest Lake across LakeGrade
More Illinois Lake Rankings
Other Grade D Lakes in Illinois
Eutrophic Lakes in Illinois
More records, surveys & data sources
EPA Impairment Status
Sparta Northwest Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_SOC · Official waterbody report · Matched by proximity (0.33 km)
Regulated Pollution Sources Nearby
6 EPA-permitted facilities operate within about 5 miles of Sparta Northwest Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Sparta Northwest Stp, City OfSparta · 0.6 mi away · NPDES IL0066133Recent violation
- Sparta Southeast Stp, City OfSparta · 2.5 mi away · NPDES IL0031160Recent violation
- Knight Hawk Coal LlcSparta · 4.2 mi away · NPDES IL0079260Recent violation
- Alpena Vision Resources LlcSparta · 2.7 mi away · NPDES IL0055824
- Alpena Vision Resources- LlcSparta · 2.7 mi away · NPDES ILD055824
- Gemini Court StpSparta · 4.5 mi away · NPDES IL0074543
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2022-10-06
Monitoring stations: 3