Blue Grass Lake is a 14-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 improving over recent sampling years. Compared to the 4 other monitored lakes in Scott County, Blue Grass Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 4.5 ft. Chlorophyll-a: 12.7 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.5 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 12.7 µg/L | C |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 14 acres |
Where to stay near Blue Grass Lake
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Fishing Blue Grass Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.415 m/yr | 4 |
| Chlorophyll-a | ↑ Improving | -51.81 µg/L/yr | 4 |
Location & Depth Map
Free interactive depth-contour map of Blue Grass Lake, reaching a maximum surveyed depth of 15 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Iowa DNR.
County Ranking
Ranked #4 of 5 lakes in Scott County
Cleaner Lakes Within 30 Miles
Blue Grass Lake holds Grade C. 2 nearby lakes hold higher grades.
- BLambach LakeScott County · 0.7 mi · Higher grade (C → B)
- CRailroad LakeScott County · 0.3 mi · Higher overall water quality score
Nearby Lakes in Scott County
Explore Blue Grass 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)
Blue Grass Lake is a man-made reservoir impounded by the Blue Grass Lake Dam (completed 1974), built primarily for recreation on the BLACK HAWK CREEK; earth-type dam, 28 ft tall and 850 ft long.
- Surface area
- 13.8 ac
- Normal storage
- 93 ac-ft
- Max storage
- 490 ac-ft
- Drainage area
- 0.8 sq mi
- Hazard class
- Significant
- Owner
- Scott County Conservation Board
All listed purposes: Recreation;Other.
Source: USACE National Inventory of Dams, NID ID IA01970 · Operator website
EPA Impairment Status
Blue Grass 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 01-NEM-68 · Official waterbody report · Matched by proximity (1.08 km)
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Blue Grass Lake under Clean Water Act (NPDES) discharge permits. 2 facilities have a reported Clean Water Act violation in the past three years.
- Davenport, City Of-West Locust LagoonDavenport · 1.2 mi away · NPDES IA0076261Recent violation
- Blue Grass City Of StpBlue Grass · 3.9 mi away · NPDES IA0028975Recent 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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-10
Monitoring stations: 1