The natural re-charge level of Loch Lomond from underground spring water is estimated at 57,100 m3 (12,600,000 imp gal) per day.

The extreme depths over most of its area causes the greater part of Loch Lomond to become stratified each summer and has characteristically low temperatures in the hypolimnion.

The City Council's response was to construct a tunnel under the Kaministiquia River to bring pure water to Fort William from Loch Lomond.

In 2006, the Bare Point Water Treatment Plant on Thunder Bay was expanded to serve the entire city from a single source.

In order to prevent pollution all activities including travel and fishing are prohibited on Loch Lomond.