WATER CLARITY (Secchi Depth)
For Trout Lake, water clarity diminished since 2016. This was expected due to the high water levels and flooding that took place in 2017. The lake took on a brownish colour also which I am told is due to staining from organic matter entering our lake.
The following are excerpts from the LLP (MOECC) on water clarity in the Canadian Shield.
“ The majority of the lakes that showed a decline (less clear) over time were located within the Canadian Shield”
The changes, where they occur, may be attributed to factors that include zebra mussel activity, changes in concentrations of algae, turbidity, total phosphorus, and/or dissolved organic carbon concentrations.
On the Canadian Shield, dissolved organic carbon (DOC) is an important determinant of water clarity. As DOC concentrations increase, water clarity (and in turn, Secchi depths) may show a corresponding decrease. This is due to dissolved solids preventing light from penetrating the water column. There is evidence that DOC concentrations are increasing in recent years in a subset of lakes on the Canadian Shield (MOECC, unpublished data).
The reasons for this decline are hypothesized to be twofold:
1) climate change causing warmer temperatures, which enhances microbiological activity in lake watershed soils; this results in a higher amount of organic carbon entering the lakes; and
2) changes in soil chemistry resulting from the recovery of acid rain, causing the soil to retain less organic carbon. -Rebecca Rossi, FOCA, 2017