Methods

In spring 2018, 10 rock weirs and 11 adjacent pool features were established as cross-sections for monitoring at Weslie Creek. Using real-time kinematic (RTK) GPS, a topographical survey was completed through the reach, at each cross-section, and at each rock weir keystone. Reach profile and cross-section elevation data were collected by taking bed and water surface elevation points with the RTK GPS every 20 cm systematically. The rock weir keystone elevation data were collected by taking elevation points with the RTK GPS on the surface of the keystone and around the exposed circumference. RTK GPS produced elevation data accurate to +/- 0.02 m. From the topographical survey, channel and rock weir geometries, and bed and water level elevation differences were determined.
Physical habitat conditions, including water depth and water temperature, were monitored continuously throughout the field season using Onset HOBO pressure transducers. One sensor was installed in a stilling well at pool 7, and another on the adjacent right bank to collect atmospheric pressure data, once per hour. The data were retrieved from each sensor every two weeks to ensure data quality and assess equipment productivity, particularly following large rainfall events. Wolman (1954) pebble counts were completed (measuring 20 pebbles at each pool feature) and monumented photographs were taken on a bi-weekly basis to identify bed substrate composition at each pool, and record changes at each pool during the field season.
Velocity measurements were collected using a three-dimensional acoustic Doppler velocimeter (ADV) (+/- 0.01 m/s). At each pool, the ADV was positioned in the flow at 60% depth. Velocity measurements were collected every 10 cm from left bank to right bank (Newson and Newson, 2000; Carollo et al., 2002). At each rock weir, velocity measurements were collected at active gap and/or over-weir flow pathways. Under intermediate and high-water level conditions, where the gap and/or over-weir flow pathways were larger in width, multiple velocity measurements were collected across the pathway, and an average “cross-section” velocity was identified for the associated pathway.
To evaluate fish passage effectiveness through the rock weirs, the swimming characteristics of local fish species were compared to the velocities through rock weir gap and over-weir flow pathways. The target fish species were identified by reviewing local conservation authority watershed and sub-watershed reports, and the swimming characteristics for each fish species were identified by reviewing relevant literature.