Upper Gar Lake is a productive, nutrient-rich eutrophic lake in Dickinson County, Iowa. Water quality is graded C 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 2 public boat landings. Compared to the 7 other monitored lakes in Dickinson County, Upper Gar Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeGrade methodology.
Watch Upper Gar Lake water quality
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 3.9 ft. Chlorophyll-a: 13.1 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 13.1 µg/L | C |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Upper Gar Lake
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Fishing Upper Gar Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.1 m/yr | 5 |
| Chlorophyll-a | ↑ Improving | -2.98 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Upper Gar Lake averages about 75°F at the surface in summer, usually warmest in Jul (about 80°F) and coldest in Jun (about 69°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 Upper Gar Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Upper Gar Lake, reaching a maximum surveyed depth of 7 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #2 of 8 lakes in Dickinson County
Cleaner Lakes Within 30 Miles
Upper Gar Lake holds Grade C. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Dickinson County
Explore Upper Gar Lake across LakeGrade
Species activity outlook by water temperature and season
Top lakes and where to stay in the Iowa Great Lakes area
Where to stay at Iowa's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
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 Upper Gar Lake under Clean Water Act (NPDES) discharge permits.
- Dry Dock DevelopmentArnolds Park · 0.4 mi away · NPDES IA0053439
- Former Okoboji Boats PropertyOkoboji · 0.7 mi away · NPDES IA0053666
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
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: 2024-09-10
Monitoring stations: 1