It’s not junk science. The shield is a deranged drainage system, meaning that there is “no coherent pattern to the rivers and lakes” (source). The fissues in the mafic rock (aka greenstone rock), which are surrounded by granite, mean that water flows hapazardly through the underground cracks and caverns (created by glacial erosion and the subsequent post-glacial rebound) to settle in the lowest areas (source).
Then please accept my apologies.