(2005-2007) Salmon River Wetland Creation

In 2005, improvements were made to Highway 401 in Shannonville, Ontario, which included rehabilitation and widening of the bridge over the Salmon River. As part of the bridge rehabilitation, pier/abutments were extended, access pads were located through floodplain and wetted channel areas, and large areas of woody debris were removed to prevent bridge scouring. The Fisheries Act authorized aquatic habitat compensation plans included an emphasis on habitat for the endangered channel darter as well as resident northern pike populations. This included construction of floating log structures, gravel liner and boulder cluster placement, and vegetated sedge hummocks.

In 2005, large pyramid-shaped hummocks (3 m by 3 m at the base) were constructed in the southeast corner of the bridge. The hummocks had a rock core, and were covered with top soil. Aquatic sedges were then planted by EcoTec on and around the nine hummocks, 22 000 plants in total. Although the sedges flourished on the hummocks, the surface area-to-volume ratio of the hummocks was small, so only a limited area was available to pike and other fish species for spawning purposes.

With consultation between EcoTec, DFO, MTO, MNR, and other engineering firms, a new design was developed. Peat pots 60 m in diameter were inverted and filled with soil, and sedges planted in each pot in the top and sides. The pots were arranged in random clusters, to mimic hummocks found in nature. A total of 24 000 sedges were planted in 463 peat pots in the northeast and southwest corners of the bridge. EcoTec installed the peat pots, and grew and planted the sedges. In addition, sedges were also planted in the northwest corner, although no hummocks were installed.

Each wetland area was created offline, protected from the river with a berm which was open to the downstream side of the channel.