Water quality can be measured in many ways. One of the easiest is with a device called a Secchi Disc. This device measures water clarity which is directly proportional to water quality. The Secchi Disc is a round disc divided into 4 quadrants like a pie. Two opposite quadrants are black and the other two are white. The disc is lowered into the water on a line marked in meters until it disappears. Next, it is slowly lifted back up and when the operator can first see the disc the depth is marked. Readings are done monthly from spring to fall. These measurements are submitted to Lake Stewards of Maine and recorded in their Maine Lakes website. We have had a monitor on Chemo Pond for decades with the exception of 1996-2007.
Water clarity is affected by many things like rainfall, wind, cloud cover, algae growth, water color, and water temperature. For instance, algae growth which is dependent on nutrients (washing in after rain storms), phosphorus (from pollution), and increased water temperature causes lower Secchi disc readings. Therefore the Secchi disc readings indicate water quality. The higher (deeper) the numbers the better the water quality. Below is a chart of the Secchi disc readings for Chemo Pond. The depth measurements are recorded in meters.
| Year | Minimum | Average | Maximum | Number of Months Recorded | ||||
| 1984 | 2.7 | 3.1 | 3.5 | 5 | ||||
| 1985 | 3.3 | 3.4 | 3.8 | 5 | ||||
| 1986 | 3 | 3.3 | 4 | 5 | ||||
| 1987 | 3 | 3.5 | 3.8 | 3 | ||||
| 1988 | 3.4 | 4 | 4.4 | 3 | ||||
| 1989 | 3 | 3.4 | 3.7 | 1 | ||||
| 1990 | 2.9 | 3.2 | 4.1 | 7 | ||||
| 1991 | 3.4 | 3.6 | 3.8 | 4 | ||||
| 1992 | 2.7 | 3.6 | 4 | 6 | ||||
| 1993 | 3 | 3.6 | 4.2 | 6 | ||||
| 1994 | 2.9 | 3.4 | 3.8 | 6 | ||||
| 1995 | 2.5 | 3.7 | 4.1 | 6 | ||||
| * | ||||||||
| 2008 | 3.4 | 4 | 4.2 | 7 | ||||
| 2009 | 3.4 | 4 | 4.3 | 7 | ||||
| 2010 | 4.2 | 4.5 | 4.7 | 4 | ||||
| 2011 | 4.4 | 4.7 | 5.5 | 5 | ||||
| 2012 | 4 | 4.3 | 4.8 | 5 | ||||
| 2013 | 3.9 | 4.1 | 4.3 | 5 | ||||
| 2014 | 4.5 | 4.7 | 5 | 3 | ||||
| 2015 | 4.5 | 4.8 | 5.1 | 3 | ||||
| 2016 | 4.1 | 4.5 | 5.3 | 4 | ||||
| 2017 | 3.8 | 4.5 | 5 | 3 | ||||
| 2018 | 3.9 | 4.8 | 5.9 | 4 | ||||
| 2019 | 2.9 | 4 | 5 | 4 | ||||
| 2020 | 4.3 | 4.8 | 5.8 | 5 | ||||
| 2021 | 3.7 | 4.2 | 5.2 | 4 |