From pristine to polluted: the cleanest and dirtiest lakes in the United States
Lake.com ranks U.S. lakes by cleanliness—Lake Superior tops the list, while Florida’s Lake Okeechobee scores lowest due to turbidity and lead.
The aptly named website, Lake.com, released a study earlier this summer detailing the cleanest and most polluted lakes in the United States.
The researchers analysed the water quality based on several variables:
- Dissolved Oxygen
- Ammonia
- Lead
- Phosphorus
- Sulfate
- Total Dissolved Solids
- Turbidity
- Difference from pH7
- Pollution.
Each lake was assigned a score of 0 to 10, with lower scores indicating better water quality, based on various factors critical to understanding whether the water supports a healthy ecosystem.
For example, dissolved oxygen levels are important, as they reflect the overall health of the lake and its ability to support fish and other aquatic life. Maintaining conditions that allow animals to thrive helps preserve ecological balance. According to Datastream, water suitable for marine life should have a dissolved oxygen level between 6.5 and 8 mg/L.
Where are the dirtiest lakes in the US?
Researchers at Lake.com found that the dirtiest lake in the U.S. was Lake Okeechobee in Florida, which received a score of 10. The lake stood out due to its high turbidity levels—measured at 34.36 NTU—and lead contamination, which was recorded at 0.67 µg/L.
According to Datastream, a lake with low turbidity typically has an NTU level below 10; 50 NTU is considered mild turbidity, and anything over 100 NTU indicates high turbidity. Analyzing turbidity is important because it affects water clarity, which in turn influences aquatic life, photosynthesis, and the overall health of the ecosystem. In lakes, the EPA says that a healthy level of turbidity will not exceed 25 NTU.
- Lake Okeechobee, Florida: 10
- American Falls Reservoir, Idaho: 7.68
- Lake Texoma, Oklahoma – Texas: 7.16
- Eufaula Lake , Oklahoma : 6.92
- Lake Clark, Alaska: 6.46
- Lake George, Florida: 6.38
- Utah Lake, Utah: 6.35
- Oneida Lake, New York: 6.04
- Pyramid Lake, Nevada: 5.84
- Richland-Chambers Reservoir, Texas : 5.6
The only other lake in the Sunshine State to make the list was Lake George. The only other state to have two states make the list was Oklahoma, with Eufaula Lake and Lake Texoma, which also sits in part of Texas.
What are the cleanest lakes in the US?
On the other hand, the cleanest lakes in the country were found to be:
- Lake Superior, Michigan – Minnesota – Wisconsin – Ontario: 0
- Lake Chelan, Washington: 0.14
- Lake Hartwell, Georgia – South Carolina: 1.73
- Lake of the Ozarks, Missouri: 1.85
- Lake Pend Oreille, Idaho: 2.09
- Lake Winnibigoshish, Minnesota: 2.2
- Kentucky Lake, Kentucky – Tennessee: 2.2
- Lake Norman. North Carolina: 2.33
- Lake Mead, Arizona – Nevada: 2.45
- Flathead Lake, Montana: 2.6
Lake Superior is the largest of the Great Lakes, containing enough water to cover all of North and South America with a foot of water. It was the only lake on the list to get a score of 0, which is the best score that a body of water could receive based on Lake.com’s methodology. None of the other Great Lakes made the top ten list.
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