Lost Grove Lake
Scott County, Iowa350 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- #2 of 5 in the county
Lost Grove Lake in Scott County, Iowa has a water quality grade of C (Fair). Water clarity: 3.9 ft visibility. Phosphorus: 31 µg/L. Chlorophyll-a (algae): 15.8 µg/L. Surface area: 350 acres.
- Clarity
- 3.9 ft
- Typical in September
- 71°F
- Area
- 350 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
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Watch Lost Grove Lake’s letter
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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.
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. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Scott County, Lost Grove Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-26. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyAlgae risk
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 3.9 ft. Phosphorus 31 µg/L. Chlorophyll-a 15.8 µg/L. TSI 56. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | Not graded |
| Phosphorus | 31 µg/L | Good |
| Chlorophyll-a (Algae) | 15.8 µg/L | Fair |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Lost Grove Lake typically sits around 71°F at the surface in September. Summer average is about 76°F. 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 →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 350 acres |
No bathymetric survey has been published for Lost Grove Lake, so its depth is not documented here.
Fishing Lost Grove Lake
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.165 m/yr | 5 |
| Phosphorus | ↓ Declining | +43.2 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +3.18 µg/L/yr | 5 |
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.
County Ranking
Ranked #2 of 5 lakes in Scott County
Nearby Lakes in Scott County
Frequently asked questions about Lost Grove Lake
Where is Lost Grove Lake?
- Lost Grove Lake is a lake in Scott County, Iowa. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lost Grove Lake?
- Lost Grove Lake in Scott County, Iowa has a water quality grade of C (Fair). Water clarity: 3.9 ft visibility. Phosphorus: 31 µg/L. Chlorophyll-a (algae): 15.8 µg/L. Surface area: 350 acres.
Is Lost Grove Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Lost Grove Lake?
- Lost Grove Lake typically sits around 71°F at the surface in September, from 21 EPA Water Quality Portal field readings (2015–2023). That is a typical value for the month, not a live reading.
Explore Lost Grove Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
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
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Where this data comes from
69 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX69 samples · 2020–2024
Analytical methods
- Unknown
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- In-Vitro Determination of Chlorophyll
- ISU modification of APHA 2130-B
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)