Sparta Northwest Lake
Randolph County, IllinoisView mapDirections
Nutrients and algae run well above the regional average.
↓ down from D at the last regrade
- Hypereutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #2 of 3 in the county
- Public access
- Limited data
Sparta Northwest Lake in Randolph County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 2.6 ft visibility. Phosphorus: 44.5 µg/L. Chlorophyll-a (algae): 32.5 µg/L.
- Clarity
- 2.6 ft
- Typical in August
- 72°F
- Type
- Hypereutrophic
- Phosphorus
- 44.5 µg/L
- Chlorophyll-a
- 32.5 µg/L
- Public access
- Yes
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Stays near Sparta Northwest Lake
Compare lakeside cabins, hotels, and vacation rentals near Sparta Northwest Lake in Randolph 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 Sparta Northwest Lake are listed below.
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Watch Sparta Northwest Lake’s letter
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Sparta Northwest Lake is a highly nutrient-loaded hypereutrophic lake in Randolph County, Illinois. Water quality is graded F based on 2 sampling years through 2022. Limited fish-species data available. Public access is available. 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 EPA, last sampled 2022-10-06. 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 F is nutrients and algae, not a swimming clearance. Sparta Northwest Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 2.6 ft of visibility. Phosphorus 44.5 µg/L. Chlorophyll-a 32.5 µg/L. TSI 62. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.6 ft | Not graded |
| Phosphorus | 44.5 µg/L | Fair |
| Chlorophyll-a (Algae) | 32.5 µg/L | Poor |
| Trophic State Index (TSI) | 62 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Sparta Northwest Lake typically sits around 72°F at the surface in August. Summer average is about 69°F. 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 →
Fishing Sparta Northwest Lake
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.
County Ranking
Ranked #2 of 3 lakes in Randolph County
Nearby Lakes With Higher Grades
Sparta Northwest Lake holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Randolph County
Frequently asked questions about Sparta Northwest Lake
Where is Sparta Northwest Lake?
- Sparta Northwest Lake is a lake in Randolph County, Illinois. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sparta Northwest Lake?
- Sparta Northwest Lake in Randolph County, Illinois has a water quality grade of F (Algae-prone). Water clarity: 2.6 ft visibility. Phosphorus: 44.5 µg/L. Chlorophyll-a (algae): 32.5 µg/L.
Is Sparta Northwest Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Sparta Northwest Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Sparta Northwest Lake?
- Sparta Northwest Lake typically sits around 72°F at the surface in August, from 562 EPA Water Quality Portal field readings (2011–2022). That is a typical value for the month, not a live reading.
Explore Sparta Northwest Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Where this data comes from
42 measurements from 3 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX42 samples · 2022
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (3)
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)