associated with each option. The embayment area and associated nursery habitat that is included in the current BBA proposal would be effectively eliminated.
Regardless of which alternative design is adopted, the determination of the amount of habitat compensatory works that will need to be incorporated into the design will need to be reassessed. We have suggested that consideration be given by all concerned parties to the idea of introducing additional habitat structure within the Broadway Drain corridor, in lieu of the originally proposed embayment area.
The report entitled “Fish and Fish Habitat Existing Conditions and Impact Assessment Report for Broadway and Healy Drain” prepared by Morrison Hershfield dated February 1, 2011, (which formed part of the EA for the project) established the requirements for the bridge and parkway project in terms of fish habitat creation. The report indicated that the following habitat quantity had to be incorporated into the Broadway Drain design:
The total length of channel in which the enhancements will occur is 545 m. With a 2 m wide channel, approximately 1,090 m2 of habitat will be enhanced for pike spawning habitat and other warm water species.
The actual length of channel that will be enhanced along the Broadway Drain is 670 m. On a water area basis, the amount of drain that will be inundated by the Detroit River at the low water datum, long-term average, and maximum monthly mean water level is approximately 1,990 m2, 5,600 m2, and 10,720 m2, respectively. Therefore, even during a low water stage, the Broadway Drain will provide 183% of the “area’ of fish habitat that the EA committed to providing. During period of average and maximum mean Detroit River water levels, more than 5.1 and 9.8 times the specified amounts will be provided.
Therefore, according to this calculation, a minimum of 900 m2 and as much as 9,600 m2 of surplus nursery habitat area is available within the new Broadway Drain corridor, depending on Detroit River water levels – habitat that is of potentially higher quality and more sustainable in the long-term than the nursery habitat that is incorporated within the original BBA infill proposal. In addition, the “benched areas” that are proposed along the south channel bank of the new channel provide addition opportunity for spawning and nursery habitat enhancement, which has not been taken into consideration in the foregoing calculations.
Therefore, we recommend that consideration be given to applying some of the surplus habitat available within the new Broadway Drain corridor to offset the BBA habitat compensatory needs.