Water quality in the Lake Nipissing - French River tributaries of Georgian Bay, Lake Huron

Session: Great Lakes Tributaries: Connecting Land and Lakes (5)

Rebecca Snider , Nipissing University , [email protected]
April James, Nipissing University, [email protected]
Huaxia Yao, ON Ministry of Environment, Conservation and Parks, [email protected]
Chris McConnell, ON Ministry of Environment, [email protected]
Tim Field, Nipissing University, [email protected]

Abstract

Lake Nipissing, the seventh largest inland lake in Ontario collects water from ~13,100 km², flowing down the French River to Georgian Bay, Lake Huron. Water quality of major inflows to Lake Nipissing is only available from the mid-1960s to early 1990s through Ontario’s Provincial Water Quality Monitoring Network (PWQMN), with large western inflows and smaller tributaries remaining largely ignored. In 2015, we set out to evaluate water quality for all inflows to the lake. During 2015/16, a monthly water quality survey of inflows was conducted and results compared to provincial and Canadian objectives. Trends in historical PWQMN records (total phosphorus (TP) and chloride) were evaluated using Mann-Kendall Trend tests. Results generally indicate a decreasing trend for TP, with 2014/15 surveys showing lower concentrations, but select inflows continuing to exhibit a percentage of samples above provincial objectives, including western inflows. For chloride, the 2015/16 survey showed higher average concentrations than historical for some inflows. Seasonal analysis indicated increasing trends for both winter (Oct-Apr) and summer (May-Sept) periods across the basin, suggesting that road salt application in this region may be affecting streamflow throughout the year. The 2015-16 survey provides new and updated assessment of water quality for inflows across the basin.