Lower Pine Lake is a 85-acre highly nutrient-loaded hypereutrophic lake in Hardin County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Water clarity is improving over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 6 other monitored lakes in Hardin County, Lower Pine Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-10-28. Grade methodology: LakeGrade methodology.
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Swimming Safety
Based on E. coli testing, Lower Pine Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 25 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 1.3 ft of visibility. Chlorophyll-a: 73.5 µg/L. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 73.5 µg/L | F |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 85 acres |
| Public Access | Yes |
Where to stay near Lower Pine Lake
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Fishing Lower Pine Lake
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 |
Recreation & Access
Water Temperature
Lower Pine Lake averages about 77°F at the surface in summer, usually warmest in Jul (about 81°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 38 field readings (2010–2023) via the EPA Water Quality Portal.
Location & Depth Map
Free interactive depth-contour map of Lower Pine Lake, reaching a maximum surveyed depth of 16 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #2 of 7 lakes in Hardin County
Cleaner Lakes Within 30 Miles
Lower Pine Lake holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Hardin County
Explore Lower Pine Lake 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)
Lower Pine Lake 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
EPA Impairment Status
Lower Pine Lake 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
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lower Pine Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger.
- Eldora City Of StpEldora · 0.8 mi away · NPDES IA0025933Major
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-10-28
Monitoring stations: 1