Lower Gar Lake is a productive, nutrient-rich eutrophic lake in Dickinson County, Iowa. Water quality is graded D based on 2 sampling years through 2024. Water clarity is declining over recent sampling years. Compared to the 7 other monitored lakes in Dickinson County, Lower Gar Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeGrade methodology.
Watch Lower Gar Lake water quality
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2.6 ft of visibility. Chlorophyll-a: 20.7 µg/L. Trophic State Index: 62.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.6 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 20.7 µg/L | D |
| Trophic State Index (TSI) | 62 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lower Gar Lake
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Fishing Lower Gar Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.15 m/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.4 µg/L/yr | 5 |
Water Temperature
Lower Gar Lake averages about 75°F at the surface in summer, usually warmest in Jul (about 81°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 27 field readings (2010–2023) via the EPA Water Quality Portal. See the full Lower Gar Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Lower Gar 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 #6 of 8 lakes in Dickinson County
Cleaner Lakes Within 30 Miles
Lower Gar Lake holds Grade D. 5 nearby lakes hold higher grades.
- AWest Okoboji LakeDickinson County · 2.5 mi · Two grade letters higher (D → A)
- CUpper Gar LakeDickinson County · 1 mi · Higher grade (D → C)
- CBig Spirit LakeDickinson County · 8.9 mi · Higher grade (D → C)
- DLake MinnewashtaDickinson County · 0.4 mi · Higher overall water quality score
- DEast Okoboji LakeDickinson County · 2 mi · Higher overall water quality score
Nearby Lakes in Dickinson County
Explore Lower 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
Iowa's cleanest and most-polluted lakes, ranked
More Iowa Lake Rankings
Other Grade D 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
5 EPA-permitted facilities operate within about 5 miles of Lower Gar Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Iowa Great Lakes Sanitary District StpMilford · 1.2 mi away · NPDES IA0059765MajorRecent violation
- Iowa Dot Ia 86 Hma Paved ShouldersMilford · 2 mi away · NPDES IA0052357
- Dctb Hwy 86 Trail - Wetland ProjectWahpeton · 2 mi away · NPDES IA0077445
- Derner'S Of Milford, Inc.Milford · 3.7 mi away · NPDES IA0077593
- Magellan Pipeline Company, L.P. - Milford TerminalMilford · 4.6 mi away · NPDES IA0071358
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
Most recent sample: 2024-09-10
Monitoring stations: 1