Study Site

The research was conducted at Weslie Creek, one of four major tributaries of the East Holland River, located in Aurora, Ontario, Canada. The East Holland River subwatershed (247 km2) originates on the north slope of the Oak Ridges Moraine and extends to the confluence with the West Holland River and Lake Simcoe’s Cook’s Bay. Surficial geology is characterized by glaciolacustrine deposits, and soils dominated by silt and clay-sized material (LSRCA, 2010). The average annual temperature is approximately 6°C, and the average annual precipitation is approximately 815 mm (LSRCA, 2010). Peak discharge events are associated with snowmelt and spring rainfall, which typically occur from March-April and April-May, respectively. According to the Ontario Flow Assessment Tool (OFAT), mean annual flow for the 9.5 km2 drainage basin including the Weslie Creek reach is 0.09 m3/s.
Following realignment to accommodate road improvements in support of a dam removal upstream, Weslie Creek was restored using natural channel design practices. A sequence of rock weirs was installed downstream of the decommissioned dam site to enhance channel and bank stability and facilitate fish passage for local species. The rock weirs are designed with various keystones and keystone sizes allowing 3-dimensional flow. Additionally, the rock weirs are asymmetrical, with alternating high and low points to enhance longitudinal connectivity through the system.