Bowker Creek is part of the Bowker Creek Watershed, a now-urbanized watershed that has been significantly affected by impenetrable surfaces, like roads, roofs and parking areas. The creek flows south from its headwaters at the University of Victoria through neighbourhoods in Saanich, Victoria, and Oak Bay, before entering the ocean near the Oak Bay Marina. In the past, Bowker Creek was fed by rainfall that ran as surface water over forests and fields, or that soaked slowly into the soil as groundwater. As the water seeped down, it was absorbed and cleansed by soil, plants, and bacteria.