Little Wall Lake
Hamilton County, IowaView mapDirections
Nutrients and algae run well above the regional average.
- Hypereutrophic
- Impaired · Algal growth
- #2 of 2 in the county
- 32 ft max depth
Little Wall Lake in Hamilton County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 0.7 ft visibility. Phosphorus: 132 µg/L. Chlorophyll-a (algae): 76.6 µg/L.
- Clarity
- 0.7 ft
- Typical in September
- 72°F
- Max depth
- ~32 ft est.
- Type
- Hypereutrophic
- Phosphorus
- 132 µg/L
- Chlorophyll-a
- 76.6 µg/L
- Trend
- ↑ Improving
Stays via Stay22
Stays near Little Wall Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Wall Lake in Hamilton County, Iowa — 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 Little Wall Lake are listed below.
Top-rated places to stay near Little Wall Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Free interactive depth-contour map of Little Wall Lake, reaching a maximum surveyed depth of 12 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
Little Wall Lake is a highly nutrient-loaded hypereutrophic lake in Hamilton County, Iowa with an estimated average depth of about 32 feet. Water quality is graded F based on 1 sampling years through 2024. Overall water quality is improving over recent sampling years. Compared to the 1 other monitored lakes in Hamilton County, Little Wall Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-30. 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 F is nutrients and algae, not a swimming clearance. Little Wall Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, turbidity. Check local advisories before you swim.
Water Quality Grade: F (Algae-prone)
Very murky, less than 0.7 ft of visibility. Phosphorus 132 µg/L. Chlorophyll-a 76.6 µg/L. TSI 77. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | Not graded |
| Phosphorus | 132 µg/L | Not graded |
| Chlorophyll-a (Algae) | 76.6 µg/L | Poor |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Temperature
Little Wall Lake typically sits around 72°F at the surface in September. Summer average is about 77°F. Usually warmest in Jul (about 82°F) and coldest in May (about 59°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Little Wall Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~32 ft est. |
| Average Depth | ~9 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Iowa has not published bathymetry for Little Wall Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Little Wall Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.025 m/yr | 5 |
| Phosphorus | ↑ Improving | -9.65 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +9.76 µg/L/yr | 5 |
EPA Impairment Status
Little Wall 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 IA 03-SSK-941 · Official waterbody report
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Little Wall Lake under Clean Water Act (NPDES) discharge permits. 4 facilities have a reported Clean Water Act violation in the past three years.
- Jewell City Of StpJewell · 2.4 mi away · NPDES IA0024422Recent violation
- Ellsworth City Of StpEllsworth · 3.5 mi away · NPDES IA0026280Recent violation
- Poet Biorefining - JewellJewell · 4.3 mi away · NPDES IA0079588Recent violation
- Ag Partners, LlcEllsworth · 4.8 mi away · NPDES IA0053034Recent 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 #2 of 2 lakes in Hamilton County
Nearby Lakes With Higher Grades
Little Wall Lake holds Grade F. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Hamilton County
Frequently asked questions about Little Wall Lake
Where is Little Wall Lake?
- Little Wall Lake is a lake in Hamilton County, Iowa. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Little Wall Lake?
- Little Wall Lake in Hamilton County, Iowa has a water quality grade of F (Algae-prone). Water clarity: 0.7 ft visibility. Phosphorus: 132 µg/L. Chlorophyll-a (algae): 76.6 µg/L.
Is Little Wall Lake safe to swim in?
- The F is nutrients and algae, not a swimming clearance. Little Wall Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth, turbidity. Check local advisories before you swim.
What is the water temperature of Little Wall Lake?
- Little Wall Lake typically sits around 72°F at the surface in September, from 29 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
How deep is Little Wall Lake?
- No published bathymetric survey covers Little Wall Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 32 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Little Wall Lake across LakeQuality
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
Where this data comes from
69 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX69 samples · 2020–2024
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)