Lake Winnipeg, among the largest freshwater lakes in the world, marks a substantial part of the western boundary of the site but suffers from pollution, eutrophication and algae blooms (all caused by activities well outside the nominated area). Increasing phosphorous influx, mostly from farming activities further to the south, has led to algae blooms of cyanobacteria in Lake Winnipeg that have nearly doubled in size since the mid 1990s (Schindler et al., 2012). These algae blooms are observable on the lake’s shoreline on the site's boundary. The critical role of clean river waters in the site for the continued health of Lake Winnipeg is widely acknowledged, and the four highest volume rivers that originate from, or flow through, the site provide 6,889,000 cubic metres of pristine, uncontaminated water to the lake annually (Wells et al., 2013).