Beginning in 1910, new technologies for mining and processing low-grade iron ore created novel environmental challenges for Minnesota’s iron mining communities. Unlike earlier high-grade iron ore which required little processing before shipping, low-grade iron ore required extensive processing near mining sites, and that processing created vast quantities of finely-ground tailings that mobilized into nearby streams, lakes, and communities. In Lake Superior’s Mesabi Range, low-grade iron ores brought significant economic benefits, but they were coupled with equally significant environmental transformations. Drawing on archival records from the first legal case in Minnesota over the pollution of surface waters from migrating mine waste, this paper asks: how did communities in the Mesabi Range respond to the new environmental challenges from low-grade iron ore? How did these negotiations between Mesabi communities, mining companies and the state play out in the courts? How did these court battles shape state mining policy? How have local heritage organizations and state agencies remembered and memorialized these environmental legacies?