Portage Inlet is impacted by runoff from the impervious surfaces (i.e. roads, buildings, parking lots) in the surrounding area. Instead of soaking into the ground, rainwater runs across these surfaces and carries pollutants into the waterway. These include oils, heavy metals, antifreeze and hydrocarbons from vehicles; pesticides and fertilizers washed off lawns and gardens. The Trans-Canada Highway is very close to the northern end of Portage Inlet, and likely contributes significant runoff to the inlet. Pollution is a concern for the survival of large Olympia oyster beds and eelgrass meadows in the area.
Portage Inlet is a receiving environment for sediment that is carried from upland areas by the two main tributaries. This is a natural process, however large areas of impervious surfaces, as well as agricultural and construction practices, can lead to increased erosion. Soils and sediment washed off the surrounding land through erosion are eventually deposited in the inlet. Accumulations of mud and sediment can cause pollutants to accumulate in the inlet, as many contaminants bind to sediment particles. If too much sediment accumulates, the inlet may eventually fill up since it is so shallow to begin with. This problem was recognized back in the 1960s and 1970s, and several proposals were put forward to open up the inlet to more ocean water circulation through canals or removing rock with explosives. However, besides the expense of such schemes, there is considerable risk that such actions would significantly and irretrievably alter the hydrology in the inlet. A more feasible approach would be to reduce erosion through landowner education and improved management practices for construction and road works. This approach would also benefit the overall condition of the inlet and the streams that feed it. (See How can I help reduce erosion?
Habitat Loss and Degradation
The shores of Portage Inlet were once a mixture of rocky shorelines, eroding bluffs, intertidal mud flats and salt marshes before the area was developed. The rough texture and complexity of rock outcrops greatly increase the available surface area, and provide nooks and crannies in which creatures can shelter, while soft sediments host a wide array of burrowing animals. Smooth surfaces such as seawalls provide little habitat in comparison. Many of the natural areas were filled in to increase the land base for development. This caused destruction of the underlying habitat. On the positive side, redevelopments of shoreline property represent opportunities for restoring natural habitat. (See Protecting shorelines and streamsides