Lost Grove Lake is a 350-acre productive, nutrient-rich eutrophic lake in Scott County, Iowa. Water quality is graded C based on 2 sampling years through 2024. Water clarity is improving over recent sampling years. Compared to the 4 other monitored lakes in Scott County, Lost Grove Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-26. Grade methodology: LakeGrade methodology.
Watch Lost Grove Lake water quality
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Swimming Safety
Swim with caution, moderate algae may be present
Water Quality Grade: C, Fair
Murky, only visible to about 3.9 ft. Chlorophyll-a: 15.8 µg/L. Trophic State Index: 58.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 15.8 µg/L | C |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 350 acres |
Where to stay near Lost Grove Lake
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Fishing Lost Grove Lake
Water Quality Trend: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.165 m/yr | 5 |
| Chlorophyll-a | ↓ Declining | +3.18 µg/L/yr | 5 |
Water Temperature
Lost Grove Lake averages about 76°F at the surface in summer, usually warmest in Jul (about 77°F) and coldest in May (about 64°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 21 field readings (2015–2023) via the EPA Water Quality Portal. See the full Lost Grove Lake water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Lost Grove Lake, reaching a maximum surveyed depth of 48 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #3 of 5 lakes in Scott County
Cleaner Lakes Within 30 Miles
Lost Grove Lake holds Grade C. 2 nearby lakes hold higher grades.
- BLambach LakeScott County · 15.9 mi · Higher grade (C → B)
- CRailroad LakeScott County · 16.2 mi · Higher overall water quality score
Nearby Lakes in Scott County
Explore Lost Grove Lake across LakeGrade
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
More records, surveys & data sources
Reservoir Info (USACE NID)
Lost Grove Lake is a man-made reservoir impounded by the Lost Grove Lake (completed 2012), built primarily for recreation on the Lost Creek; earth-type dam, 75 ft tall and 1,165 ft long.
- Surface area
- 350 ac
- Normal storage
- 6,080 ac-ft
- Max storage
- 9,595 ac-ft
- Drainage area
- 7.1 sq mi
- Hazard class
- High
- Owner
- Iowa Department of Natural Resources
Source: USACE National Inventory of Dams, NID ID IA04083 · Operator website
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Lost Grove Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Princeton City Of StpPrinceton · 4.4 mi away · NPDES IA0033227Recent violation
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)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-08-26
Monitoring stations: 1