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Secchi Disk Reading

The latest recorded reading as of 9/26/2023 was 13 feet.

Whether you are a nearby resident, lakefront property owner, local business, or a visitor, the NPA wants to keep you informed. With the assistance of Colby College interns, our lake scientists have been collecting water quality data on a weekly basis. We will post the Secchi disk readings as they are collected throughout the remainder of the summer. This information can also be found on signs in front of Tri Pond Variety and the former Smithfield Fire Station. Read below for more information on Secchi disk readings and water quality parameters specific to North Pond.


Water quality measurements are collected using a Secchi disk, which is a weighted disk that is lowered into the water to determine how deep the sunlight can penetrate into the water. A high amount of sediment or algae causes a lower Secchi disk reading which indicates deteriorating or poor water quality.


These are the water quality parameters specific to North Pond that have been created by one of our scientists:


13 feet or greater: Good

13-10 feet: Fair

10-7 feet: Poor

7-3 feet: Algal Bloom

3 feet or less: Potentially Toxic Algal Bloom


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