Beneficial Use Impairments (BUIs) are a set of 14 different parameters used when designating an Area of Concern (AOC) under the U.S. – Canada Great Lakes Water Quality Agreement.
The St. Marys River was identified as an Area of Concern because 9 out of 14 beneficial uses were considered to be impaired, and 1 required further assessment.
Today, 6 out of the 14 possible impairments remain on the Canadian Side of the river, and 3 out of 14 remain on the U.S. Side.
The following is a summary of the current impairments in the St. Marys River Area of Concern:
| No. | bENEFICIAL USE IMPAIRMENT | sTATUS IN
cANADA |
sTATUS IN tHE u.s. |
|---|---|---|---|
| 1. | Restrictions on Fish and Wildlife Consumption | Impaired | Impaired |
| 2. | Tainting of Fish and Wildlife Flavour | Never Impaired | Never Impaired |
| 3. | Degradation of Fish and Wildlife Populations | Impaired | Not Impaired
(2019) |
| 4. | Fish Tumors and Other Deformities | Impaired | Impaired |
| 5. | Bird and Animal Deformities or Reproductive Problems | Not Impaired (2015) | Not Impaired (2014) |
| 6. | Degradation of Benthos | Impaired | Impaired |
| 7. | Restrictions on Dredging Activities | Impaired (Change to Not Impaired recommended) | Not Impaired (2018) |
| 8. | Eutrophication and Undesirable Algae | Not Impaired (2018) | Not Impaired (2017) |
| 9. | Restrictions on Drinking Water Consumption or Taste and Odour Problems | Never Impaired | Never Impaired |
| 10. | Beach Closings | Not Impaired (2018) | Not Impaired (2016) |
| 11. | Degradation of Aesthetics | Not Impaired (2018) | Not Impaired (2014) |
| 12. | Added Cost to Agriculture and Industry | Never Impaired | Never Impaired |
| 13. | Degradation of Phytoplankton and Zooplankton | Never Impaired | Never Impaired |
| 14. | Loss of Fish and Wildlife Habitat | Impaired | Not Impaired (2019) |