Green Belt Lake
Black Hawk County, IowaView mapDirections
Nutrients and algae sit mid-range for this region.
↑ up from D at the last regrade
- Eutrophic
- #2 of 7 in the county
Green Belt Lake in Black Hawk County, Iowa has a water quality grade of C (Fair). Water clarity: 2.4 ft visibility. Phosphorus: 57 µg/L. Chlorophyll-a (algae): 18.6 µg/L.
- Clarity
- 2.4 ft
- Typical in September
- 75°F
- Type
- Eutrophic
- Trend
- → Stable
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Watch Green Belt Lake’s letter
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Free interactive depth-contour map of Green Belt Lake, reaching a maximum surveyed depth of 18 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Green Belt Lake is a productive, nutrient-rich eutrophic lake in Black Hawk County, Iowa. Water quality is graded C based on 2 sampling years through 2024. Water clarity is improving over recent sampling years. Compared to the 6 other monitored lakes in Black Hawk County, Green Belt Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-28. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Very murky, less than 2.4 ft of visibility. Phosphorus 57 µg/L. Chlorophyll-a 18.6 µg/L. TSI 62. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.4 ft | Not graded |
| Phosphorus | 57 µg/L | Fair |
| Chlorophyll-a (Algae) | 18.6 µg/L | Fair |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Green Belt Lake typically sits around 75°F at the surface in September. Summer average is about 79°F. Usually warmest in Jul (about 81°F) and coldest in Sep (about 75°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 32 field readings (2010–2023) via the EPA Water Quality Portal. See the full Green Belt Lake water temperature breakdown →
Fishing Green Belt Lake
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.022 m/yr | 4 |
| Phosphorus | → Stable | -0.4 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +8.71 µg/L/yr | 4 |
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Green Belt Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- John Deere Waterloo Works (Drive Train Operations)Waterloo · 2.5 mi away · NPDES IA0000060Major
- John Deere Product Engineering CenterCedar Falls · 1.4 mi away · NPDES IA0062481Recent violation
- John Deere Foundry WaterlooWaterloo · 2.3 mi away · NPDES IA0069485
- Magellan Pipeline Company, L.P.Waterloo · 3.3 mi away · NPDES IA0072672
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 7 lakes in Black Hawk County
Nearby Lakes in Black Hawk County
Frequently asked questions about Green Belt Lake
Where is Green Belt Lake?
- Green Belt Lake is a lake in Black Hawk County, Iowa. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Green Belt Lake?
- Green Belt Lake in Black Hawk County, Iowa has a water quality grade of C (Fair). Water clarity: 2.4 ft visibility. Phosphorus: 57 µg/L. Chlorophyll-a (algae): 18.6 µg/L.
Is Green Belt Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Green Belt Lake?
- Green Belt Lake typically sits around 75°F at the surface in September, from 32 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Green Belt Lake across LakeQuality
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
Where this data comes from
70 measurements from 1 monitoring station, 2021–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX70 samples · 2021–2024
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- In-Vitro Determination of Chlorophyll
- ISU modification of APHA 2130-B
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)