Kentucky's Cleanest Lake: Lake Beshear (Christian County)

The single cleanest lake in Kentucky is Lake Beshear (Christian County, KY), with the highest combined water quality score in our 2026 dataset (grade B). Cleanliness is measured by Secchi depth (clarity), total phosphorus, and chlorophyll-a — all sourced from EPA Water Quality Portal and state agency sampling. The full top 25 ranked list appears below.

Ranking the cleanest Kentucky lakes means picking the basins with the strongest nutrient-and-algae letters, then the clearer water among lakes that share a letter. Lake Beshear (Christian County, KY) leads the list with a grade of B, with Moffit Lake close behind.

The top of the cleanest-lakes list is dominated by deep, glacial, cold-water basins — the same basins that produce the A-grade bracket overall. The pattern is not coincidence: depth and watershed land-use are the dominant inputs to water-clarity and nutrient-loading both.

Rank	Lake	County	Grade	Clarity	Phosphorus	Chlorophyll-a	Area
1	Lake Beshear (Christian County, KY)	Christian	B	—	30 µg/L	—	794 acres
2	Moffit Lake	Union	B	—	30 µg/L	—	49 acres
3	Pennyrile Lake	Christian	B	—	30 µg/L	—	47 acres
4	Cap Mauzy Lake	Union	B	—	30 µg/L	—	83 acres
5	Greenbo Lake	Greenup	C	—	30 µg/L	—	181 acres
6	Smoky Valley Lake	Carter	C	—	30 µg/L	—	35 acres
7	Corinth Lake	Grant	C	—	30 µg/L	—	96 acres
8	Panbowl Lake	Breathitt	C	—	30 µg/L	—	98 acres
9	Mill Creek Lake	Wolfe	C	—	30 µg/L	—	41 acres
10	Fishpond Lake	Letcher	C	—	30 µg/L	—	32 acres
11	Combs Lake	Clay	C	—	30 µg/L	—	36 acres
12	Lake Cannigo	Nicholas	C	—	30 µg/L	—	114 acres
13	Williamstown Lake	Grant	C	—	30 µg/L	—	300 acres
14	Greenbrier Creek Reservoir	Montgomery	C	—	30 µg/L	—	-
15	Sand Lick Creek Lake	Fleming	C	—	30 µg/L	—	74 acres
16	Campbell County Lake	Campbell	C	—	30 µg/L	—	193 acres
17	Long Run Lake	Jefferson	C	—	30 µg/L	—	27 acres
18	Kincaid Lake	Pendleton	C	—	30 µg/L	—	179 acres
19	Doe Run Lake	Kenton	C	—	30 µg/L	—	51 acres
20	Kentucky Lake	Calloway	C	—	32.1 µg/L	—	-
21	Laurel Creek Reservoir	McCreary	C	—	30 µg/L	—	54 acres
22	Cannon Creek Lake	Bell	C	—	30 µg/L	—	243 acres
23	Corbin City Reservoir	Laurel	C	—	30 µg/L	—	-
24	Herb Smith Lake	Harlan	C	—	30 µg/L	—	219 acres
25	Wood Creek Lake	Laurel	C	—	30 µg/L	—	672 acres

Get updates when Kentucky's cleanest-lake list changes

New nutrient and algae samples can move a lake up or down this ranking. Unsubscribe anytime.

All-states list →Minnesota version →Wisconsin version →Illinois version →Best swimming lakes in Kentucky →All Kentucky lakes →Most polluted lakes →

Clearest lakes in Kentucky by water clarity

“Clearest” ranks by Secchi depth — how far you can see into the water — which can differ from the combined cleanliness score above. The clearest water in Kentucky is Rough River Lake at 6.4 ft of Secchi visibility.

1. Rough River Lake — 6.4 ft, Breckinridge County
2. Yatesville Lake — 6.1 ft, Lawrence County
3. Nolin Lake — 5.5 ft, Edmonson County
4. Paintsville Lake — 5.2 ft, Johnson County
5. Lake Cumberland — 4.1 ft, Pulaski County

Frequently Asked Questions

What is the cleanest lake in Kentucky?

Lake Beshear (Christian County, KY) has the highest water quality score in our 2026 Kentucky dataset (grade B). Lakes are graded A to F on nutrients and algae — total phosphorus, total nitrogen, chlorophyll-a, and turbidity — measured against the EPA National Lakes Assessment 2022 condition classes for that lake's own ecoregion, so a lake is judged against the lakes it would naturally resemble. Cleanliness here means a low nutrient load and little algae, measured directly from EPA and state DNR samples; where two lakes tie on the letter, the deeper Secchi reading ranks first.

What is the most polluted lake in Kentucky?

Among monitored Kentucky lakes, Energy Lake ranks among the most polluted by combined phosphorus and chlorophyll-a load. See our full ranking on the most-polluted-lakes trend page for state-by-state details.

Where in Kentucky has the cleanest water?

Kentucky's clearest waters are concentrated in deeper, lower-nutrient glacial basins with forested or low-agriculture watersheds. Among the current top-ranked lakes above, counties like Christian, Union, and Grant produce the highest-scoring lakes.

What is the clearest lake in Kentucky?

Rough River Lake is the clearest lake in Kentucky by water clarity, with a Secchi depth of 6.4 feet — the deepest transparency in our 2026 dataset. "Clearest" ranks by Secchi depth (how far you can see into the water) specifically, while "cleanest" combines clarity with phosphorus and chlorophyll-a. See our full clearest-lakes ranking for Kentucky for the top 25 by Secchi clarity.

Are these lakes safe to swim in?

Not on the letter alone. An A or B is a nutrients-and-algae classification, not a swimming clearance — it does not measure E. coli, cyanotoxins, or a posted beach closure, and a lake with low chlorophyll-a can still bloom. Always check current posted advisories before swimming: water quality changes seasonally, especially in late summer when blue-green algae bloom risk peaks.

How are these grades calculated?

The letter is nutrients and algae — phosphorus, nitrogen, chlorophyll-a, and turbidity — scored against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion, not a Kentucky-only 0–100 average and not an equal-weight mean with Secchi. Water clarity is shown; it is not scored. Lakes without enough recent sampling are UNRATED. Our methodology page has the full rubric.

What are the top 5 cleanest lakes in the US?

There is no single national ranking of cleanest lakes — each state agency uses different metrics. Crater Lake (Oregon) is widely cited as the clearest US lake, with Secchi depths over 30 m. Lake Tahoe and Lake Superior are also top-tier nationally. Within Kentucky, the 25 lakes ranked above are the graded lakes with the highest letters in our 2026 dataset.

How we rank cleanest lakes

Cleanliness here means three things working together:

Secchi clarity — how deep you can see into the water (in feet). Greater depth = clearer water = lower suspended sediment and algae.
Total phosphorus — the nutrient that fuels algae. Lower phosphorus levels mean less algae growth potential.
Chlorophyll-a — the green pigment in algae. Direct measurement of how much algae is currently in the water.

Each signal is normalized against Kentucky state norms and combined into a single 0–100 score. The lakes above are sorted by that combined score.Full methodology →

More on clean water

Cleanest and Dirtiest Lakes in America 2026

The cleanest and dirtiest U.S. lakes in the monitoring record, ranked on EPA nutrient and algae condition classes across thousands of graded lakes.

Lake Water Quality Grades Explained: What A–F Means

How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.

Cleanest Small Lakes in America 2026

The cleanest U.S. lakes under 500 acres, ranked on measured nutrients, algae, and water clarity — with the size cutoff applied to the lake, not the sample.

How to Choose a Clean Lake for a Cabin or Weekend Trip

A practical checklist for picking a lake with good water quality — clarity, phosphorus, algae history, depth, and the data to check before you commit.

Where to stay near Kentucky's cleanest lakes

Compare cabins, resorts, and rentals around Lake Beshear (Christian County, KY) and the other lakes in this ranking, with live availability and prices for your trip. Each pin on the map is one of the ranked lakes above.

Top-rated places to stay near Lake Beshear (Christian County, KY)

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Source: EPA National Aquatic Resource Surveys, 2026.