Lake.com ranks Lake Chelan cleanest and Great Salt Lake dirtiest for 2026

Lake.com released a 2026 ranking of the cleanest and dirtiest U.S. lakes on World Lake Day, using water-quality data from 100 of the largest lakes. Lake Chelan in Washington topped the clean list, while Utah’s Great Salt Lake ranked worst, underscoring wide differences in lake conditions nationwide.

Why it matters: - The ranking gives travelers, local officials and lake users a simple snapshot of water quality at major U.S. lakes. - The results highlight how much lake conditions can vary, even among some of the country’s most popular destinations. - The findings also reinforce the need for ongoing monitoring and local water-quality guidance.

What happened: - Lake.com released its 2026 ranking of the cleanest and dirtiest lakes in the United States on Aug. 27, World Lake Day. - Lake Chelan in Washington ranked as the cleanest lake in the analysis. - The Great Salt Lake in Utah ranked as the dirtiest lake in the analysis. - The study examined 100 of the largest lakes in the U.S. and ranked 67 lakes with up-to-date chemical composition data.

The details: - Lake.com used water-quality data from the National Water Quality Monitoring Council. - Researchers evaluated eight indicators: dissolved oxygen, ammonia, lead, phosphorus, sulfate, total dissolved solids, turbidity and pH. - The ranking used the most recent 12-month median for each indicator. - The data window ran from Jan. 1, 2021, through July 30, 2026. - Among the 10 cleanest lakes, available measurements showed turbidity below 5.26 NTU, total dissolved solids below 200 mg/L and dissolved oxygen above 8 mg/L. - Lake Chelan posted turbidity of 2.00 NTU and total dissolved solids of 30.25 mg/L. - Lake Superior, spanning Michigan, Minnesota and Washington, had the lowest turbidity in the analysis at 0.54 NTU. - Lake Martin in Alabama rounded out the top three cleanest lakes with turbidity of 1.28 NTU, dissolved oxygen of 8.15 mg/L and a pH close to neutral. - Among the dirtiest lakes, available measurements showed turbidity as high as 65.55 NTU, total dissolved solids above 180 mg/L and dissolved oxygen as low as 3.65 mg/L. - Great Salt Lake’s pollution score was driven mainly by total dissolved solids of 134,500 mg/L, far above any other lake in the study. - Great Salt Lake’s terminal saline nature means salts and minerals build up as water leaves mainly through evaporation, which materially affects its ranking. - Lake McConaughy in Nebraska and Lake Winnebago in Wisconsin placed second and third among the dirtiest lakes. - Devils Lake in North Dakota recorded the highest sulfate concentration in the study at 639 mg/L. - Lake Moultrie in South Carolina recorded the highest lead concentration at 17.2 µg/L. - The report says it presents the information impartially and offers a factual base for communities and agencies to address water-quality concerns. - Lake.com said it is focused on stays and experiences by the water and features more than 75,000 vacation homes across North America and Europe.

Between the lines: - Great Salt Lake’s ranking is not a simple pollution story because its naturally high mineral content from evaporation dominates the result. - The clean-lake results suggest that some large U.S. lakes still offer strong water quality for recreation, even as conditions vary sharply by location. - The inclusion of both chemical and physical measures makes the ranking more useful for comparing overall lake conditions, not just one pollutant.

What's next: - Lake.com says travelers should check local water-quality information and posted guidance before swimming, boating or fishing. - The company directs readers to the full report for more detail. - Continued monitoring will likely remain important as lake conditions change over time and by location.

The bottom line: - Lake Chelan emerged as the cleanest of the large U.S. lakes studied, while Great Salt Lake ranked dirtiest largely because of its extreme natural salinity.