Lake of the Ozarks ranks among cleanest US lakes, study finds

One of Missouri’s largest lakes is among the cleanest in the nation, according to a new report.

A study conducted by Lake.com, a vacation rental platform for properties near or on water, focused on the 100 largest lakes in the United States and their chemical data from Jan. 1, 2020, to July 15, 2025.

The lakes were tested for eight of the most commonly measured characteristics that can suggest their cleanliness, including pH, ammonia and lead.

What’s the cleanest lake in Missouri?

Lake.com rated the Lake of the Ozarks as the fourth-cleanest lake in the country.

The lake earned a 1.85 out of 10 in its pollution score, bolstered primarily by its low pH and sulfate levels, as well as its lack of lead and ammonia.

The report listed the following measurements for the lake:

• Dissolved oxygen: 7.5 mg/L
• Phosphorus: 0.01 mg/L
• Sulfate: 1.66 mg/L
• Turbidity: 2.3 NTU
• Difference from pH7: 2.3 pH
• Pollution score: 1.85/10

What did Lakes.com have to say about Lake of the Ozarks?

“With 54,000 surface acres and 1,150 miles of shoreline, more coastline than the entire state of California, it is the largest non-flood-control man-made lake in the United States. The lake’s distinctive serpentine shape, stretching 92 miles from Bagnell Dam to the lake’s western reach, earned it the nickname “The Magic Dragon.” The lake extends across four Missouri counties, Camden, Morgan, Miller, and Benton, with the city of Osage Beach at the busy southeastern junction of the main channel and the Grand Glaize arm serving as the region’s commercial hub.”

What are the cleanest lakes in the nation?

Lake.com lists these lakes as the cleanest in the nation:

1. Lake Superior (Michigan/Minnesota/Wisconsin/Ontario)
2. Lake Chelan (Washington)
3. Lake Hartwell (Georgia/South Carolina)
4. Lake of the Ozarks (Missouri)
5. Lake Pend Oreille (Idaho)
6. Lake Winnibigoshish (Minnesota)
7. Kentucky Lake (Kentucky/Tennessee)
8. Lake Norman (North Carolina)
9. Lake Mead (Arizona/Nevada)
10. Flathead Lake (Montana)

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What are the dirtiest lakes in the nation?

Lake.com lists the following lakes as the dirtiest lakes in the nation:

1. Lake Okeechobee (Florida)
2. American Falls Reservoir (Idaho)
3. Lake Texoma (Oklahoma, Texas)
4. Eufaula Lake (Oklahoma)
5. Lake Clark (Alaska)
6. Lake George (Florida)
7. Utah Lake (Utah)
8. Oneida Lake (New York)
9. Pyramid Lake (Nevada)
10. Richland-Chambers Reservoir (Texas)