High-resolution (0.5m) backscatter from the Stamp Sands of Lake Superior collected using a Norbit iWBMSh multibeam echosounder during 2021 (GeoTIFF, UTM Zone 16N, NAD 83, NAVD 88)

The erosion and active transport of legacy mine tailings (called “stamp sands”) are impacting native fish species and aquatic habitats on a shallow water rocky reef complex along the Keweenaw Peninsula of Michigan called Buffalo Reef. Stamp sands are spreading from an old mill site at the Town of Gay and settling on the reef. Multiple surveys have documented the underwater migration of toxic, metal-rich stamp sands and progressive burial of areas of hard/complex lakefloor, such as cobble fields. The finer-grained, muddy fraction of the mine tailings has been winnowed by waves and currents and transported to unknown locations in deeper waters offshore. High-resolution geophysical mapping of the bay in 2018 revealed a complex pattern [...]