Cleanest Lake in Nebraska: Lake C W Mcconaughy (2026)

The single cleanest lake in Nebraska is Lake C W Mcconaughy, ranked first on its measured clarity and nutrients in the 2026 sampling record. Cleanliness here is measured by Secchi depth (clarity), total phosphorus, and chlorophyll-a — all sourced from EPA Water Quality Portal and state agency sampling, shown as reported. The full top 25 ranked list appears below.

The "cleanest" ranking on LakeQuality is built from the measured nutrients and algae — phosphorus and chlorophyll-a read against EPA National Lakes Assessment 2022 ecoregion classes. Secchi clarity is shown and used only as a tiebreak. The cleanest Nebraska lake on the current data is Lake C W Mcconaughy.

The top of the cleanest-lakes list is dominated by deep, glacial, cold-water basins — the same basins that carry the lowest nutrient readings 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	Clarity	Phosphorus	Chlorophyll-a	Area
1	Lake C W Mcconaughy	Keith	7.2 ft	57.6 µg/L	6.9 µg/L	-
2	Sherman Reservoir	Sherman	2.4 ft	99.7 µg/L	4.4 µg/L	2,868 acres
3	Lake Minatare	Scotts Bluff	5.5 ft	52.4 µg/L	2.8 µg/L	2,195 acres
4	Hershey Lake	Lincoln	13.6 ft	51.4 µg/L	2.1 µg/L	-
5	Bridgeport Middle Lake	Morrill	18.9 ft	—	2 µg/L	-
6	Hugh Butler Lake	Frontier	2.8 ft	82.9 µg/L	5.9 µg/L	4,060 acres
7	Calamus Reservoir	Garfield	3.6 ft	124.5 µg/L	26.1 µg/L	5,123 acres
8	Cub Creek Lake	Keya Paha	4.9 ft	48.1 µg/L	8.4 µg/L	31 acres
9	Lake Maloney	Lincoln	2.1 ft	47.8 µg/L	10.2 µg/L	-
10	Merritt Reservoir	Cherry	2 ft	147 µg/L	92.1 µg/L	3,222 acres
11	Pelican Lake	Cherry	1.2 ft	210 µg/L	88.9 µg/L	-
12	Oliver Reservoir	Kimball	1.7 ft	71.8 µg/L	7.9 µg/L	264 acres
13	Smith Lake	Sheridan	1.7 ft	248 µg/L	56.1 µg/L	425 acres
14	Crescent Lake	Garden	0.8 ft	132.5 µg/L	109.6 µg/L	-
15	Goose Lake	Holt	1 ft	170 µg/L	32.6 µg/L	-
16	Swanson Reservoir	Hitchcock	2.6 ft	90 µg/L	7.1 µg/L	7,940 acres
17	Box Butte Reservoir	Dawes	5.6 ft	51.5 µg/L	4.5 µg/L	1,799 acres
18	Harry Strunk Lake	Frontier	2.5 ft	67.6 µg/L	10.3 µg/L	5,793 acres
19	Pibel Lake	Wheeler	2 ft	979 µg/L	54.9 µg/L	26 acres
20	Kramper Lake	Dakota	4.5 ft	46.3 µg/L	13.3 µg/L	226 acres
21	Kirkman'S Cove Lake	Richardson	1.4 ft	132 µg/L	20.5 µg/L	155 acres
22	Enders Reservoir	Chase	2.8 ft	56.4 µg/L	10.3 µg/L	2,557 acres
23	Johnson Lake	Gosper	2.8 ft	62.3 µg/L	11.3 µg/L	-
24	Harlan County Reservoir	Harlan	2.8 ft	201 µg/L	12.6 µg/L	13,600 acres
25	Lake Wanahoo	Saunders	2.4 ft	92.4 µg/L	28 µg/L	662 acres

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

All-states list →Clearest lakes in Nebraska (by Secchi clarity) →Minnesota version →Wisconsin version →Illinois version →Best swimming lakes in Nebraska →All Nebraska lakes →

Clearest lakes in Nebraska 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 Nebraska is Bridgeport Middle Lake at 18.9 ft of Secchi visibility.

1. Bridgeport Middle Lake — 18.9 ft, Morrill County
2. Hershey Lake — 13.6 ft, Lincoln County
3. Elwood Reservoir — 10 ft, Gosper County
4. Lake Carter P Johnson — 8.3 ft, Sioux County
5. Crystal Cove Lake — 7.8 ft, Dakota County

See the full clearest-lakes ranking for Nebraska →

Frequently Asked Questions

What is the cleanest lake in Nebraska?

Lake C W Mcconaughy ranks first on measured clarity and nutrients in the 2026 Nebraska sampling record. Each lake's nutrient and algae readings — total phosphorus, total nitrogen, chlorophyll-a, and turbidity — are shown beside the EPA National Lakes Assessment 2022 condition class for that lake's own ecoregion, so a reading is compared against the lakes it would naturally resemble. LakeQuality publishes no letter grade. Cleanliness here means a low nutrient load and little algae, measured directly from EPA and state DNR samples; where two lakes tie on nutrients and algae, the deeper Secchi reading ranks first.

Where in Nebraska has the cleanest water?

Nebraska'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 Lincoln, Frontier, and Cherry produce the highest-scoring lakes.

What is the clearest lake in Nebraska?

Bridgeport Middle Lake is the clearest lake in Nebraska by water clarity, with a Secchi depth of 18.9 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 Nebraska for the top 25 by Secchi clarity.

Are these lakes safe to swim in?

Not on these readings alone. Clarity and nutrient readings are not a swimming clearance: they do 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 is this ranking calculated?

Lakes are ranked on phosphorus, chlorophyll-a and clarity as measured by EPA and state agency sampling, read against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion, not a Nebraska-only 0–100 average. Water clarity is shown beside the nutrient readings. Lakes with limited sampling do not headline the table.

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 Nebraska, the 25 lakes ranked above have the lowest nutrient and algae readings 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 Nebraska 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

Lake Water Quality Explained: What the Readings Mean

How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading 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 Nebraska's cleanest lakes

Compare cabins, resorts, and rentals around Lake C W Mcconaughy 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 C W Mcconaughy

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Source: EPA National Aquatic Resource Surveys, 2026.