For decades, Harold “Hal” Arthur has been ferrying monitors to test the water quality of Moose Pond. In his aluminum boat, Hal takes them to two sites—one off of Camp Winona and the other in the north basin.
“I love the lake and trying to do the little bit I can to help keep it pristine,” is Hal’s answer when asked why he’s been doing this for so long. “I also love the interaction with all of the interns from Bridie to all the guys who work on the Milfoil project on the Songo River. You name them and I’ve worked with them on Moose Pond.” When he began, Hal did some of the testing, but since the state instituted stricter rules and required training, he’s content to ferry the monitors about in his boat and jot down readings for them.
Testing is not only important to properly identify current or potential issues, but also to establish data for future comparisons.
First, the Secchi disk is used to measure the clarity of the water. The Secchi disk is a metal or plastic disk with two black and white quadrants painted on top. It’s attached to a calibrated metric tape. The monitor slowly lowers the disk into the water, while simultaneously looking through an aquascope to note when the white quadrants are no longer visible. The disk is raised a bit and lowered again to make sure it’s at the right depth. The clearer the water, the deeper the disk is lowered. The metric reading of the tape at the surface of the water is recorded.
The next test involves a dissolved oxygen meter and sensing probe. The probe is attached to the instrument via a long cord. Since the monitor knows the depth of the water, the probe is lowered meter by meter to one meter above the ﬂoor of the pond. This prevents it from getting ruined or stuck in the bottom sediment. At every meter, the probe is jigged and the monitor records an accurate digital reading of the water temperature and oxygen level. This data is double-checked at two or three readings.
Cold water contains more oxygen than warm water. Fish, like landlocked salmon and lake trout, need the oxygen in the deeper, cooler water to survive. Too much algae growing in the warmer surface water may prevent that from happening.
After getting an oxygen and temperature proﬁle, the monitor takes water samples to measure phosphorus and chlorophyll. Though phosphorus is a natural element in soil, when too much of it ﬂows from other sources, it becomes a signiﬁcant threat to water quality because algae thrive on it. As algae grow, water clarity decreases. Chlorophyll, the green plant pigment, is measured to determine the size of the algae population.
For these tests, the monitor collects water to be evaluated in a laboratory. First, the bottles and beakers are labeled with information about Moose Pond. After rinsing hands, bottles and beakers to remove contaminates, the core tube is lowered to the thermocline, clamped and quickly pulled to the surface. It ﬁlls with water during this process. The end is placed in a mixing jug and the clamp released, allowing the water to ﬂow. Then it’s poured into several bottles and vials to be tested for pH, color, alkalinity and conductivity, phosphorus analysis and chlorophyll content.
In addition, this summer LEA hired Researcher Amanda Pratt to conduct additional tests for Gloeotrichia echinulata, a cyanobacteria, plus iron and aluminum in bottom sediments. Amanda also used temperature sensors to take readings every ﬁfteen minutes over several months on Moose Pond. In a separate article you can read about her Gloeo ﬁndings. As of this writing, she has not yet completed her studies of the two chemicals and the temperature. Overall, her research will give LEA and the Moose Pond Association a baseline from which to compare future data.
In the past few years, the water quality tests have yielded worse results than had been recorded historically. The scientiﬁc details of the 2013 report will be available later this year at mainelakes.org.
We all need to pitch in, like Hal, and do our part to help keep this the pristine body of water we all love. Whether helping with water testing or carrying out erosion control efforts on your own property, everyone can contribute.