Eutrophication or Undesirable Algae BUI 8 Overview

Not Impaired

Why was this BUI originally listed as not impaired?

• The status of this BUI was listed as not impaired in the 1991 Stage 1 RAP Report because eutrophication had not been documented in the river and “is unlikely to occur due to the short retention time of the river” (MDNR and OMOE 1991).
• This status remained in the 2010 Stage 2 RAP Report

This BUI will be considered to be ‘not impaired’ when….

The nutrient status of the waters of the Detroit River will support the establishment of mesotrophic conditions in the Western Basin of Lake Erie, and the shoreline of the river will support minimal grown of attached algae (e.g., Cladophora).

What was done?

• Data for the assessment of this BUI are very limited; however, it is clear that algal blooms and other signs of cultural eutrophication (e.g., low dissolved oxygen) are not a problem in the Detroit River itself. This is in large part due to the water current; the average time for water to pass through the Detroit River is only 19 to 21 hours (Derecki 1984)
• Studies from GLIER reveal that total phosphorus concentrations of the waters entering Lake Erie from the Detroit River and upstream sources are approximately 20 µg/L, sufficient to support mesotrophic conditions in the western basin of Lake Erie. Therefore, is it recommended that the status of Eutrophication or Undesirable Algae remain listed as not impaired
• The focus of future monitoring for this beneficial use (no undesirable algae) will be on the potential for impacts to Lake Erie

When did the status change?

• The status remained not impaired in 2010

The bi-national connection: What is the U.S. doing?

• The Detroit River AOC includes 11 BUIs on the American side and 14 on the Canadian side. BUI 8 is unique to the Canadian AOC and is not recognized as an impairment in the American AOC
• Check out the Friends of the Detroit River to learn more about what our American partners are doing for the river

Where can I learn more?

Detroit River Canadian Remedial Action Plan: Stage 2 Report (2010): pages 68-76.