Lake Water Quality 2006 Report - Lakefield Herald

ANOVA analysis as no suitable data were found for other lakes: Balsam, Big Bald,Buckhorn, Cameron, Clear, Katchewanooka, Pigeon, Upper Stoney, Stony and Sturgeon.The majority of the archived data and subsequent analyses used suggest thatphosphorus levels have declined in the Kawartha Lakes watershed, which is congruentwith the finding of Robillard and Fox (2006); however, the results should beinterpreted cautiously. There is evidence that phosphorus levels are closely linkedwith precipitation patterns, where wet years have higher phosphorus concentrationsthan dry years (Novotny and Olem, 1994). According to Environment Canada, theKawartha Lakes area had a much higher average rainfall in 1972 than it did in either1976 or 2005. Similarly, 1976 had a higher average rainfall than 2005; however, it ispossible that phosphorus levels have been decreasing over time. Fortunately, thedata from Sturgeon Lake were collected annually and demonstrate a clear decreasingtrend in phosphorus concentrations over time. It would appear that phosphorusconcentrations have remained relatively stable in Sturgeon Lake from 1988 throughto 2005 at approximately 17 µg/L.Finally, the results authenticate that lake phosphorus concentrations increase aswater flows east through the lake continuum from Balsam Lake to Lovesick Lake. Theincreasing logistic pattern is then disrupted as low-phosphorus water enters thesystem from Upper Stoney Lake and dilutes the high-phosphorus water of LovesickLake below Burleigh Falls in Stony Lake. The lakes’ phosphorus concentrationscontinue to increase after dilution at Stony Lake as demonstrated by the successivelyhigher phosphorus concentrations in Clear and Katchewanooka Lakes.Phosphorus levels have declined approximately 7 µg/L over the past 20 years and arecurrently around 14 µg/L. Phosphorus concentrations are known to increase in wetyears and decrease in dry years: 2005 was a dry year. Phosphorus concentrationsincrease as water flows from Balsam Lake along the Trent-Severn Waterway to RiceLake. There is a slight dilution and resultant reduction in phosphorus concentrationas low-phosphorus water enters the system from Upper Stoney Lake via Stony Lake.41