Williamson Pond Max Depth is a 25-acre highly nutrient-loaded hypereutrophic lake in Lucas County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Water clarity is improving over recent sampling years. Compared to the 3 other monitored lakes in Lucas County, Williamson Pond Max Depth ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-02. 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
Very murky, less than 1.6 ft of visibility. Chlorophyll-a: 73.9 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.6 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 73.9 µg/L | F |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 25 acres |
Where to stay near Williamson Pond Max Depth
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Fishing Williamson Pond Max Depth
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.088 m/yr | 4 |
| Chlorophyll-a | ↓ Declining | +10.72 µg/L/yr | 4 |
Water Temperature
Williamson Pond Max Depth averages about 78°F at the surface in summer, usually warmest in Jul (about 82°F) and coldest in May (about 71°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 26 field readings (2010–2023) via the EPA Water Quality Portal. See the full Williamson Pond Max Depth water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Williamson Pond Max Depth, reaching a maximum surveyed depth of 14 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #4 of 4 lakes in Lucas County
Cleaner Lakes Within 30 Miles
Williamson Pond Max Depth holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Lucas County
Explore Williamson Pond Max Depth across LakeGrade
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Williamson Pond Max Depth is a man-made reservoir impounded by the Williamson Pond Dam (completed 1915), built primarily for recreation on the TR-ENGLISH CREEK; earth-type dam, 32 ft tall and 575 ft long.
- Surface area
- 25 ac
- Normal storage
- 223 ac-ft
- Max storage
- 484 ac-ft
- Drainage area
- 2.28 sq mi
- Hazard class
- Low
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA01296 · Operator website · Matched by proximity (0.06 km)
EPA Impairment Status
Williamson Pond Max Depth 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 04-LDM-1058 · Official waterbody report · Matched by proximity (0.34 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-10-02
Monitoring stations: 1