WILTON — On Wilson Lake on Friday, the air temperature was 23 degrees Celsius and 72 degrees Fahrenheit. The wind was from the west at 12-15 knots per hour.

Fourth-graders from Academy Hill School recorded those details, among others, in sailors’ logs during boat trips on the lake described as “living lab” lessons. 

Pupils were taken on rides aboard the Melinda Ann, Maine Lakes Society’s research boat, to collect data using special instruments.

Dr. Peter Kallin, president of the society, asked the children to identify a disk, divided into four alternating black and white sections, attached to a rope. 

They knew it was a Secchi disk, used to describe the clarity of a lake.

Kallin said the test is “surprisingly repeatable” because it can be done numerous times in the same area and will give the same results.

“Ten to 12 meters are the readings for the clearest lakes in Maine,” he said. “Lake Tahoe is the clearest lake in the United States with a reading of 35 meters.” 

The boat’s captain, Maine Lakes Society educator Phil Mulville, described how an aquascope works.

“The glare from the sun and the waves make it hard to see the Secchi disk,” he said. “The aquascope has a clear lens on one end. You look through the other end. It is like a long, extended diving mask.” 

The pupils used both tools and obtained a clarity reading of 5.5 meters.

“Wilson Lake is a relatively average Maine lake,” Kallin said.

He explained why the temperature of the water at the top of a lake is warmer than at the bottom.

“Cold water is denser and stays on the bottom,” he said. “Water freezes at 32 degrees Fahrenheit. Hydrogen bonding makes ice lighter; otherwise, lakes would freeze from the bottom up.” 

He said students had recorded a water temperature of 8 degrees Celsius at the lake’s deepest point.

Mulville explained how a benthic dredge works to take samples from the lake’s bottom. Pupils helped him obtain a sample with only a dead leaf found. A second sample revealed a “scud” macroinvertebrate arthropod and live weeds.

Kallin showed the students how to tell native from invasive weeds based on the types of leaves.

The students also got to operate an ROV, a remotely operated vehicle, that can go to a depth of 300 feet. Maine’s deepest lake, Sebago, is 314 feet deep.

The program was part of a U.S. EPA Clean Water Act grant obtained by Wilton and Friends of Wilson Lake to reduce nonpoint source pollution in the Wilson Lake watershed.

pharnden@sunmediagroup.net

Maine Lakes Society President Peter Kallin explains to Academy Hill School fourth-graders how the Secchi disk is used to compare water quality in lakes. The pupils were studying Wilson Lake aboard the society’s research boat, the Melinda Ann, on Friday.  (Pam Harnden/Livermore Falls Advertiser)

Academy Hill School fourth-graders watch as Melinda Ann Captain Phil Mulville, a Maine Lakes Society educator, at right, explains how a benthic dredge is used to collect samples from a lake bottom. The hands-on learning experience was part of a U.S. EPA Clean Water Act grant obtained by Wilton and the Friends of Wilson Lake. (Pam Harnden/Livermore Falls Advertiser)

Maine Lakes Society educator Phil Mulville explains some of the features on the remotely operated vehicle that fourth-graders from Academy Hill School in Wilton got to drive while aboard the Melinda Ann. The students learned about some research equipment and collected data from Wilson Lake. (Pam Harnden/Livermore Falls Advertiser)

Academy Hill School fourth-graders learned about data collection methods while aboard the Maine Lakes Society’s research boat, the Melinda Ann on Wilson Lake in Wilton on Friday. From left are Damien Stevens, Mason Reed, Noah Daoust, Madison Cloutier and Maekayla Conley. (Pam Harnden/Livermore Falls Advertiser)

Academy Hill School fourth-graders collected data from Wilson Lake while aboard the Maine Lakes Society’s research boat, the Melinda Ann, on Friday. Society President Peter Kallin, right, is aboard during the second of three trips on the lake. (Pam Harnden/Livermore Falls Advertiser)