a) The high lake levels that have persisted since the improvements were substantially completed has served to reduce the average flow velocities due to greater backwater effects. This has allowed sediments to deposit at a higher rate than will occur when lake levels are low and the channel functions in a free discharge condition.

b) During their final review of the design drawings, DFO requested that the rock sheeting along the north drain bank be top-dress above the water level at the time of construction. The request was accommodated in order to obtain DFO’s consensus with the design. We understand that the request was made in anticipation that top-dressing the rock would facilitate and accelerate establishment of vegetation of the lower slope.

Unfortunately, immediately after the rock was top-dressed and the area was seeded, lake levels began to rise, which eventually completely submerged the rock. As noted, the high-water levels have persisted since 2017. We suspect that the unvegetated soil provided a substantial source of sediment to the drain, which has intensified and accelerated the sedimentation that is being observed.

We anticipate that when lake levels return to normal or below normal levels, average stream flow velocities during significant rainfall events will increase enough to scour the light sediments from the habitat features. No measures are recommended in the interim.

10.6 Future Channel Cleaning

Any sediment generated by future maintenance operations should be disposed of off-site.

Due to the highly industrialized land-use that predominates the current watershed of the Broadway Drain, there is a high potential for any sediments that enter the Broadway Drain to be chemically impacted. Run-off from the bridge plaza and PAR is likely to contain elevated chemical concentrations, regardless of the effectiveness of the SWM ponds that are incorporated into the works. Therefore, should the drain ever require a bottom cleaning, excavated materials should be tested to confirm the most appropriate sediment disposal strategy.

11.0 Approvals

As noted, the review and approval process were governed by the requirements of the Bridge To

Strengthen Trade Act. In addition, a permit was obtained from the Essex Region Conservation

Authority.

12.0 Fish Plan

As we introduced in Section 5.2, the process of our obtaining meaningful input at the design development stage with regard to the Fisheries Act was challenged due to the impact of the Bridge To Strengthen Trade Act, and the review protocols prescribed therein. At the outset of the Drainage Act process, DFO expressed their preference that the commitments made in the approved EA be followed. Our opinion that the approach prescribed in the EA would have resulted in an inappropriate and unsustainable design was also stated in Section 5.2. DFO