The state Department of Environment, Great Lakes and Energy sent a violation notice Wednesday to Erickson's Inc., the owner of the riverside property leased by Detroit Bulk Storage.
A dock at the site collapsed Nov. 26, discharging an unknown amount of crushed limestone into the river, along with asphalt and contaminated soils. The department said testing determined that contaminant levels in the water were not detectable or well below quality standards.
The spill violated the Natural Resources and Environmental Protection Act, which prohibits discharging such material into state waters without a permit, district supervisor Andrew Hartz of the department's Water Resources Division said in a letter to Erickson's.
Steve Erickson, president of the company based in Grand Rapids, Michigan, declined to comment.
The letter ordered the company to provide a restoration plan with a schedule for removing “all unauthorized fill material" from the river and to consider action to prevent the exposed shoreline from further erosion.
The department also sent a letter to Detroit Bulk Storage instructing the company to prevent exposure to hazardous substances in soils at the site.