Vulnerability of Drinking Water Treatment Plants to Low Water Levels in the St. Lawrence River

Abstract

This project’s main objective was to determine the vulnerability of water treatment plants (WTPs) along the lower St. Lawrence River to water level fluctuations, which included the effects of both regulation and climate change. Of the 30 WTPs investigated, three were found to be vulnerable to flow conditions experienced in the past (last 100 years). The vulnerability being dictated by the impossibility of supplying the maximum water demand for which the plant was originally designed. For large facilities that dispose multiple equipments (e.g., two wells or two intakes), a large fraction of the production could be maintained at a critical level. For smaller plants, on the other hand, the situation could be more critical. Insufficient water in the well, caused by low water levels in the river, could cause pumping problems or interrupted distribution, but this can be remedied more easily than in larger plants.