Current Status: Impaired

Degradation of Benthos remains one of the remaining Beneficial Use Impairments in the St. Marys River Area of Concern.

Although benthic community health has improved considerably and many restoration actions have been completed, additional evidence is needed before this BUI can be redesignated as Not Impaired. Continued sediment remediation and long-term monitoring will help determine when benthic communities have recovered sufficiently to meet the established delisting criteria.

The ongoing work to address this BUI is an important part of restoring the overall ecological health of the St. Marys River and moving closer to the eventual delisting of the Area of Concern.

Why Was This BUI Listed?

When the St. Marys River was designated a Great Lakes Area of Concern, historical industrial activity, municipal discharges, and shoreline alterations had contributed contaminants to portions of the river.

Studies found that benthic communities in some areas differed from those expected under healthy conditions. In particular, locations containing contaminated sediments often supported fewer pollution-sensitive species and a greater number of organisms that are tolerant of environmental stress.

Because benthic community health is closely linked to sediment quality, these findings suggested that historical contamination and habitat degradation were affecting sediment-dwelling organisms.

As a result, Degradation of Benthos was identified as a Beneficial Use Impairment.

What Has Changed?

Over the past several decades, significant efforts have been made to improve environmental conditions throughout the St. Marys River.

Actions completed include:

• Upgrades to municipal wastewater treatment facilities.
• Reductions in industrial contaminant discharges.
• Improvements to stormwater management.
• Habitat restoration and shoreline enhancement projects.
• Sediment investigations and environmental monitoring.
• Planning and implementation of contaminated sediment remediation projects.

Researchers have conducted multiple benthic community assessments throughout the Area of Concern to determine whether conditions have improved.

These studies found that many locations within the river support healthy and diverse benthic communities. However, some areas continue to show signs of environmental stress, particularly where contaminated sediments remain.

Recent assessments indicate that while substantial progress has been made, the evidence is not yet sufficient to conclude that benthic communities throughout the Area of Concern are fully comparable to suitable reference locations.

Status on the Canadian Side

On the Canadian side of the St. Marys River Area of Concern, Degradation of Benthos remains Impaired.

Current assessments indicate that:

• Benthic community health has improved in many areas of the river.
• Some locations continue to exhibit signs of environmental stress.
• Contaminated sediments remain a concern in certain areas, particularly the Algoma Boat Slip.
• Additional remediation and monitoring are required before the impairment can be reassessed.
• The delisting criteria have not yet been fully achieved.

While conditions have improved significantly since the Area of Concern was first designated, further work is needed to demonstrate that benthic communities have fully recovered.

What Happens Next?

The remaining work for this BUI is closely linked to ongoing sediment remediation efforts within the Area of Concern.

Future actions include:

• Completion of contaminated sediment remediation projects, including work within the Algoma Boat Slip.
• Continued monitoring of benthic communities throughout the river.
• Follow-up assessments to evaluate ecosystem recovery after remediation.
• Comparison of benthic community conditions with suitable reference locations.
• Reassessment of the BUI once sufficient monitoring data become available.

Scientists expect that improvements in sediment quality will support continued recovery of benthic organisms over time.