Lay Monitoring Water Clarity Report to Lake Groton Association, 2004

For a number of years we have been measuring water clarity of the lake during the summer season. We do this as volunteers to the Department of Environmental Conservation, which collects similar data from all over Vermont.

Using a SECCI disk, we take readings in designated spots in the southern and northern parts of the lake. The disk is a heavy steel plate painted in black and white quadrants that we lower into the water. We measure how deep the disk can be lowered and still be seen.

We take readings about once a week from June through August, about ten times a season. The following are this year’s readings (in meters [1M = about 3 1/2 ft.]):

Date Station 1 (south) Station 2 (north)

6/1 4.0 3.8
6/6 3.0 3.8
6/14 4.2 4.1
7/5 3.6 3.0
7/17 3.3 3.6
7/25 3.2 2.8
7/26 3.4 3.0
8/10 3.3 3.0
8/15 3.5 3.6
8/22 4.3 5.0

Many factors affect water clarity. Runoff is an important factor, with less clarity to be expected following spring runoff and after significant amounts rainfall.

In the future, we are hoping to add tests for water quality to our Lay Monitoring project.

[Cathleen C. Donath, September 4, 2004]