Buffalo Reef Stamp Sands: Movement and Composition Characterized in July 2019 Study
Posted on: September 4, 2019
This NOAA 2010 LiDAR of Grand (Big) Traverse Bay, shows many significant underwater structures including the stamp sand “trough” (5) and stamp sands moving into the north and western cobble fields of Buffalo Reef (3 & 4). (Source: Kerfoot et al., 2019)

The study titled Lidar (light detection and ranging) and benthic invertebrate investigations: Migrating tailings threaten Buffalo Reef in Lake Superior, by W. Charles Kerfoot, Martin M. Hobmeier, Robert Regis, Varsha K. Raman, Colin N. Brooks, Robert Shuchman, Mike Sayers, Foad Yousef, and Molly Reif, was published by the Journal of Great Lakes Research and made available online August 8, 2019.


LiDAR from 2008 to 2016 shows places of erosion (red) and deposition (blue). The Underwater stamps sand bars are clearly moving south towards Buffalo Reef. (Source: Kerfoot et al., 2019)

This study involved LiDAR over-flight investigations from 2008 to 2016, arial photographs, and detailed sediment sampling of Big Traverse Bay. Researchers used images over multiple years to characterize the erosion and deposition of stamp sands both on and off-shore. Sediment samples were used to quantify the percentage of stamp sands in sand mixtures around Buffalo Reef and copper concentrations were estimated based on those stamp sand. The study also looked at what impact these concentrations of stamp sands have on lake bottom organisms.


These four LiDAR images from 2008, 2011, 2010 and 2013 show the stamp sands moving into and filling up the trough just north of Buffalo Reef. (Source: Kerfoot et al., 2019)

The study shows that stamp sands are moving in on the Northern portion of the Buffalo Reef. The impact on lake bottom organisms that live on the Buffalo Reef cobbles is significant:

Above 26% stamp sand, almost all taxa showed severe density depression. Above 75% stamp sand concentrations […], there simply were no observed organisms, a virtual desert

– Kerfoot et al., 2019

Buffalo Reef cobbles are home to diatoms and bacteria that live on the rocks as a film (a,b). These communities are killed off when stamp sands move in, as they have begun to do in the northern cobble field of Buffalo Reef (c). (Source: Kerfoot et el., 2019)

The underwater “trough” north of Buffalo Reef, which once acted as a sink, has now transitioned into a source of stamp sands. Stamp sands have accumulated to the point of overflowing from the middle section of the trough. The study also shows that the main shoreline source of stamp sands is transitioning from the original Gay pile to the stamp sand beach just south of it. The stamp sand beach is wider and higher than the original white beach margin and is spilling over the Traverse River seawall, as evidenced by trace amounts of stamp sands in the white sand beach just south of the Traverse River (12.3 – 16.9%).


The Original tailings pile off of Gay Michigan is undergoing active erosion on Lake Superior’s shoreline (a). The stamp sand beach south of the original pile has flowed over the Traverse River seawall and is discolouring the water (b). (Source: Kerfoot et al., 2019)

Cleanup efforts are considered a high priority with multiple millions of dollars in funding already allocated to dredging efforts that began this summer. Plans to dredge the “trough” and the Traverse River should provide several years time to plan long-term mitigation before Buffalo Reef is engulfed in Stamp Sands.


Citation

W.C. Kerfoot, M.M. Hobmeier, R. Regis, et al., Lidar (light detection and ranging) and benthic invertebrate investigations: Migrating tailings threaten Buffalo Reef in Lake Superior, Journal of Great Lakes Research, Available online August 8, 2019 https://doi.org/10.1016/j.jglr.2019.07.009


In the News

APNews – EPA contributes $3.7 mill to Stamp Sands cleanup

Previous Infosuperior articles on Buffalo Reef

Feb. 2019: Comments Sought on Potential Long-term Solutions for Encroaching Stamp Sands at Buffalo Reef

Oct. 2018: Dredging Contract Awarded to Protect Buffalo Reef

Apr. 2018: Saving Buffalo Reef


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