Water Science & Technology Vol 55 No 5 pp 1–8 © Environment Canada 2007 doi:10.2166/wst.2007.155

Off flavours in large waterbodies: physics, chemistry and biology in synchrony

S.B. Watson^*, M. Charlton^*, Y.R. Rao^*, T. Howell^**, J. Ridal^***, B. Brownlee^*, C. Marvin^* and S. Millard^****

The Laurentian Great Lakes of North America are a drinking water source for millions of Canadian and US consumers. These waterbodies have undergone extensive change over the past century as a result of widespread degradation and remediation. Many of the Lakes are prone to taste and odour (T&O), and although these outbreaks have been poorly monitored, evidence suggests that they are increasing in frequency. Tracing and controlling T&O in such large systems presents a challenging task, due to their physical size and complexity. This paper presents an overview of recent investigative and management approaches to T&O in Lake Ontario and its outflow, the St. Lawrence River. We have identified three distinct patterns of T&O in these source-waters, caused by geosmin and 2-methylisoborneol and differing in their planktonic and benthic sources, and temporal and spatial dynamics. Each pattern has required a different approach by scientists and management, in partnership with the water industry. We have shown these T&O outbreaks are caused and moderated by physical, chemical and biological mechanisms over a spectrum of spatial and temporal scales. Canadian municipalities affected by these outbreaks have been key to the investigation of the links between T&O and ecosystem processes with the aim to develop more proactive water treatment and long-term management.

Keywords: Geosmin; Great Lakes; Lake Ontario; 2-methylisoborneol; proactive management; taste and odour

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