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Volunteer Water sampling on Lake Scugog by Ken Oldfield, Scugog Lake Stewards Inc. For me, the first sign of spring is the arrival, usually in early April, of a parcel containing six boxes addressed to yours truly. The ladies at the post office always ask me: “What's in there?.....How come such a big package weighs so little?” My answer > is that it is this year's water sampling kits. courtesy of the volunteer Lake Partner Program run by the Ontario Ministry of the Environment. | have been doing this sampling on Lake Scugog for the Lake Partner Program since | moved to Port Perry in 1997. Via this network of volunteers, many hundreds of Ontario's lakes are monitored annually for the MOE for water clarity and nutrient loading. a warm water lake, Lake Scugog is sampled every month from May to October. My sampling site is at one of the few relatively deep basins on the East side of the lake out from Caesarea where the lake bottoms out at seven meters or so. Lowering the Secchi disc. Getting ready to test water clarity. The science is really simple Testing water clarity the world over is extremely easy. A small black and white weighted disc, called a Sec- chi disc, is lowered into the water on a measured cord. When the disc totally disappears from sight, the clarity reading is measured in depth on the cord. In summer, we are often lucky to get a clarity reading of 1 meter. In Spring, the clarity reading has been as high as 2.5 metres. This compares with readings carried out on a cold water lake near Algonquin Park, Percy Lake, where the clarity reading in late summer was almost 5 meters. “ Scugog's turbid, greenish water is an indication of high levels of nitrogen and mainly phosphorus present in } a the water column. This combined with blue skies, sunshine and warm temperatures, nurture blooms of uni-cel- lular floating algae called phytoplankton. This is what makes our lake turn a green colour during the summer and makes its clarity readings plummet. x Testing for phosphorus In addition to the Secchi disc readings for water clarity, water samples are taken to measure levels of phosphorus in the water which are sent to the MOE for testing. My data over the years of sampling the east side of lake confirms that it comes in at around 20 parts phosphorus per million. From the Lake Scu- gog Environmental Management Plan testing we know that the west side of the lake has higher levels of phosphorus present in the water. These 20 ppm readings and above are in sharp contrast to northern Percy Lake which came in with a phosphorus count of less than 5 parts per million. However, many of you may have noticed that water clarity on our lake has improved in recent years. The zebra mussel, an invasive species, is thought to be the main reason for this improvement. This tiny animal is now present in our lake in great numbers and feeds on the phytoplankton suspended in the water column. The result is clearer water. Clearer water, of course, allows - more sunlight to penetrate to the bottom facilitating denser and deeper weed a growth. But that, as they say, is another story! Preparing the phosphorus sample. Photos by Cathy Otattd Editor: Life on the Lake: Barbara Karthein bkarthein@yahoo.ca 985-0958 Scugog Lake Stewards h