5. CONSTRUCTION IMPACTS AND MITIGATION MEASURES

5.1

POTENTIAL IMPACTS TO FISH AND FISH HABITAT

Potential impacts and losses of fish and fish habitat resulting from construction within the Broadway Drain, Detroit River and/or the drainage channel will occur as a result of the proposed construction works, however, these negative effects will be short-term and temporary in nature assuming all mitigations and offsetting measures are implemented effectively. During the 2010 field investigations it was noted that Broadway Drain is considered a warm / cool water municipal drain that has the potential to support a warm and cool water seasonal fishery which was confirmed through communications with DFO as well as field observations in 2015/16. Any potential impacts which may result from construction are considered temporary and can be mitigated. The final design for the realignment of Broadway Drain includes several key features that will be implemented to offset fish habitat impacted and/or lost within the Broadway Drain and/or other watercourses/surface water features within the Early Works site.

Potential land-based and water-based impacts may occur throughout the existing Broadway Drain, Detroit River and drainage channel during construction. If work is completed during a low flow periods, direct impacts to fish and fish habitat could be minimized, however, potential impacts that may result from the proposed work include:

• Alteration of riparian vegetation by equipment access which may affect bank stability and expose soils;
• Increased erosion potential leading to the release of sediment and or change in sediment concentrations;
• Temporary and permanent change in habitat structure and cover, food supply, and nutrient concentrations as a result of the placement of materials; and
• Introduction of contaminants including deleterious substances (e.g., fuel, oil, etc.) into the watercourse through the use of industrial equipment and construction debris which may lead to changes in water chemistry and/or cause direct mortality to aquatic organisms.

Disturbances as a result of the Broadway Drain realignment and the infilling of a portion of the drainage channel will result in serious harm to fish as seasonal fish habitat will be lost, however, losses from the infilling areas will be offset within the lower reach of the Broadway Drain. So long as the proposed mitigation requirements are adhered to during construction, no long-term residual effects are anticipated. Existing baseline conditions in the Broadway Drain, as well as the Detroit River, including temperature, flow, and suspended sediment are not expected to change as a result of this work. To mitigate potential changes in baseline conditions in areas downstream of active construction works, all in-water work will be either completed in the dry or in isolation of the remaining downstream section of the drain.

5.2 RESIDUAL IMPACTS  

It must be stated that the proposed work will follow the construction schedule and as a result some in-water work will be completed outside the warm/cool water fisheries timing window (no in-water work between March 15 and June 30) implemented by DFO. Work occurring within the Detroit River must adhere to the warm/cool water fisheries timing window and this is reflected in the tentative schedule shown in Table 3. Notification will be sent to DFO prior to any work commencing within the Detroit River. This notification will be sent at a minimum of 7 working days prior to commencing work within the Detroit River.

It is acknowledged that the in-water works identified within this document will cause serious harm to fish within the Broadway Drain, Healy Drain, Detroit River and the drainage channel as proposed works will result in the alteration and/or destruction of fish habitat. This includes the infilling and abandoned sections of existing channels, as well as the footprint on