QUEBEC LAKE SURVEY .1. STATISTICAL ASSESSMENT OF SURFACE-WATER QUALITY

The Quebec Lake Survey (QLS) was conducted as part of the Quebec Spatial Lake Acidity monitoring network (RESSALQ). A total of 1253 lakes were visited at winter-time between 1986 and 1990, to quantify and to extrapolate the water quality status of a statistically representative set of lakes to the target lake population of five subregions. Water quality is strongly influenced by terrain characteristics. The airborne anthropogenic pollution also influences greatly the water chemistry of lakes in areas receiving high SO4 depositions. Within the QLS study area, the Cote-Nord subregion is the most sensitive and the most affected by acidity. Yet, these acidic conditions can be mostly explained by the combination of an important organic acid contribution and the extreme sensitivity of the area. The Outaouais and Abitibi areas also present great proportions of acidic lakes. The acidity of these lakes originates mostly from anthropogenic sources.