Pine Lake South Beach is a 85-acre highly nutrient-loaded hypereutrophic lake in Hardin County, Iowa. Water quality is graded F based on 1 sampling years through 2023. Water clarity is improving over recent sampling years. Compared to the 6 other monitored lakes in Hardin County, Pine Lake South Beach ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2023-09-27. Grade methodology: LakeGrade methodology.
Watch Pine Lake South Beach water quality
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Swimming Safety
Based on E. coli testing, Pine Lake South Beach routinely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 28.6% of 105 samples across 7 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Iowa’s current beach and health-department advisories before swimming.
Water Quality Grade: F, Very Poor
Very murky, less than 1.4 ft of visibility. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.4 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 85 acres |
Where to stay near Pine Lake South Beach
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Fishing Pine Lake South Beach
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.034 m/yr | 5 |
| Chlorophyll-a | ↓ Declining | +11.78 µg/L/yr | 5 |
Water Temperature
Pine Lake South Beach averages about 79°F at the surface in summer, usually warmest in Jul (about 82°F) and coldest in May (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 86 field readings (2010–2022) via the EPA Water Quality Portal. See the full Pine Lake South Beach water temperature breakdown →
Location
County Ranking
Ranked #3 of 7 lakes in Hardin County
Cleaner Lakes Within 30 Miles
Pine Lake South Beach holds Grade F. One nearby lake has a higher grade.
Nearby Lakes in Hardin County
Explore Pine Lake South Beach 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)
Pine Lake South Beach is a man-made reservoir impounded by the Lower Pine Lake Dam (completed 1922), built primarily for recreation on the PINE CREEK; earth-type dam, 33 ft tall and 450 ft long.
- Surface area
- 85 ac
- Normal storage
- 360 ac-ft
- Max storage
- 924 ac-ft
- Drainage area
- 15.47 sq mi
- Hazard class
- Significant
- Owner
- Iowa Department of Natural Resources
All listed purposes: Recreation;Other.
Source: USACE National Inventory of Dams, NID ID IA01346 · Operator website · Matched by proximity (0.46 km)
EPA Impairment Status
Pine Lake South Beach is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 02-IOW-758 · Official waterbody report · Matched by proximity (0.47 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: 2023-09-27
Monitoring stations: 1