Blue Grass Lake
Scott County, Iowa14 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- Impaired · Algal growth
- #3 of 5 in the county
Blue Grass Lake in Scott County, Iowa has a water quality grade of C (Fair). Water clarity: 4.5 ft visibility. Phosphorus: 63 µg/L. Chlorophyll-a (algae): 12.7 µg/L. Surface area: 13.8 acres.
- Clarity
- 4.5 ft
- Area
- 14 acres
- Type
- Eutrophic
- Phosphorus
- 63 µg/L
- Chlorophyll-a
- 12.7 µg/L
- Trend
- ↑ Improving
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Watch Blue Grass Lake’s letter
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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.
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 #3 for water quality.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-09-10. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyModerate
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. Blue Grass Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 4.5 ft. Phosphorus 63 µg/L. Chlorophyll-a 12.7 µg/L. TSI 58. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.5 ft | Not graded |
| Phosphorus | 63 µg/L | Poor |
| Chlorophyll-a (Algae) | 12.7 µg/L | Good |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 14 acres |
No bathymetric survey has been published for Blue Grass Lake, so its depth is not documented here.
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 |
| Phosphorus | ↑ Improving | -41.11 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -51.81 µg/L/yr | 4 |
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.
County Ranking
Ranked #3 of 5 lakes in Scott County
Nearby Lakes in Scott County
Frequently asked questions about Blue Grass Lake
Where is Blue Grass Lake?
- Blue Grass 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 Blue Grass Lake?
- Blue Grass Lake in Scott County, Iowa has a water quality grade of C (Fair). Water clarity: 4.5 ft visibility. Phosphorus: 63 µg/L. Chlorophyll-a (algae): 12.7 µg/L. Surface area: 13.8 acres.
Is Blue Grass Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Blue Grass Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for algal growth. Check local advisories before you swim.
Explore Blue Grass Lake across LakeQuality
More Iowa Lake Rankings
Other Grade C Lakes in Iowa
Eutrophic Lakes in Iowa
Where this data comes from
39 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_WQX39 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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)