Boltz Lake
Grant County, Kentucky92 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from C at the last regrade
- Eutrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #3 of 3 in the county
- 39 ft max depth
- Public access
Boltz Lake in Grant County, Kentucky has a water quality grade of D (Nutrient-rich). Phosphorus: 37.3 µg/L. Surface area: 91.8 acres.
- Max depth
- ~39 ft est.
- Area
- 92 acres
- Type
- Eutrophic
- Phosphorus
- 37.3 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Stays near Boltz Lake
Compare lakeside cabins, hotels, and vacation rentals near Boltz Lake in Grant County, Kentucky — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Boltz Lake are listed below.
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Watch Boltz Lake’s letter
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Boltz Lake is a 92-acre productive, nutrient-rich eutrophic lake in Grant County, Kentucky with an estimated average depth of about 39 feet. Water quality is graded D based on 1 sampling years through 2022. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Grant County, Boltz Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, KY DOW, last sampled 2022-09-15. Grade methodology: LakeQuality methodology.
What Boltz Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Grade onlyElevated nutrients
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 D is nutrients and algae, not a swimming clearance. Boltz Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
No clarity data. Phosphorus 37.3 µg/L. TSI 56. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 37.3 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~39 ft est. |
| Average Depth | ~14 ft est. |
| Surface Area | 92 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Kentucky has not published bathymetry for Boltz Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Boltz LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Boltz Lake
Water Quality Trend: ↓ Declining
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↓ Declining | +2.26 µg/L/yr | 3 |
Reservoir Info (USACE NID)
Boltz Lake is a man-made reservoir impounded by the Boltz Lake Dam (completed 1956), built primarily for recreation on the Eagle Creek; earth-type dam, 62 ft tall and 600 ft long.
- Surface area
- 91.8 ac
- Normal storage
- 2,200 ac-ft
- Max storage
- 2,800 ac-ft
- Drainage area
- 3.11 sq mi
- Hazard class
- High
- Owner
- COMMONWEALTH OF KENTUCKY
Source: USACE National Inventory of Dams, NID ID KY00032 · Operator website
EPA Impairment Status
Boltz Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit KY-305 · Official waterbody report
County Ranking
Ranked #3 of 3 lakes in Grant County
Nearby Lakes With Higher Grades
Boltz Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Grant County
Frequently asked questions about Boltz Lake
Where is Boltz Lake?
- Boltz Lake is a lake in Grant County, Kentucky. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Boltz Lake?
- Boltz Lake in Grant County, Kentucky has a water quality grade of D (Nutrient-rich). Phosphorus: 37.3 µg/L. Surface area: 91.8 acres.
Is Boltz Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Boltz Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
How deep is Boltz Lake?
- No published bathymetric survey covers Boltz Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 39 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 91.8 acres.
Are there boat ramps on Boltz Lake?
- Boltz Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Boltz Lake. Public access is listed as yes.
Explore Boltz Lake across LakeQuality
More Kentucky Lake Rankings
Other Grade D Lakes in Kentucky
Eutrophic Lakes in Kentucky
Where this data comes from
22 measurements from 2 monitoring stations, 2013–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- KY WQX
21KY_WQX22 samples · 2013–2022
Analytical methods
- Phosphorus by Colorimetry
- Total Phosphorus After Block Digestion
- Turbidity by Nephelometry
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory