Silver Lake is a highly nutrient-loaded hypereutrophic lake in Palo Alto County, Iowa. Water quality is graded F based on 2 sampling years through 2024. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Palo Alto County, Silver Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-11. 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 1.2 ft of visibility. Chlorophyll-a: 53.9 µg/L. Trophic State Index: 72.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.2 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 53.9 µg/L | F |
| Trophic State Index (TSI) | 72 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Silver Lake
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Fishing Silver Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.019 m/yr | 5 |
| Chlorophyll-a | ↑ Improving | -17.53 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Silver Lake averages about 75°F at the surface in summer, usually warmest in Jul (about 80°F) and coldest in Jun (about 70°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 27 field readings (2010–2023) via the EPA Water Quality Portal. See the full Silver Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Silver Lake, reaching a maximum surveyed depth of 6 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #2 of 3 lakes in Palo Alto County
Cleaner Lakes Within 30 Miles
Silver Lake holds Grade F. 5 nearby lakes hold higher grades.
- CUpper Gar LakeDickinson County · 26.3 mi · Two grade letters higher (F → C)
- DLost Island LakePalo Alto County · 10.1 mi · Higher grade (F → D)
- DStolley Pit LakeClay County · 17.6 mi · Higher grade (F → D)
- DLake MinnewashtaDickinson County · 25.8 mi · Higher grade (F → D)
- DGustafson LakeBuena Vista County · 17 mi · Higher grade (F → D)
Nearby Lakes in Palo Alto County
Explore Silver Lake across LakeGrade
More Iowa Lake Rankings
Other Grade F Lakes in Iowa
Hypereutrophic Lakes in Iowa
More records, surveys & data sources
EPA Impairment Status
Silver 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 04-UDM-1229 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Silver Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Ayrshire, City Of StpAyrshire · 2.9 mi away · NPDES IA0079677Recent violation
- Ayrshire, City Of WtpAyrshire · 2.5 mi away · NPDES IA0084361
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: 2024-09-11
Monitoring stations: 1