Mark Heaton

Ontario Streams, Aurora, Ontario Canada, Canada

The goal of restoring Atlantic salmon in Lake Ontario and several of its north-shore tributaries has been the impetus for instream barrier mitigation in several “best bet” rivers for over 20 years.  Habitat fragmentation, as a result of dam construction, was one of the major reasons why the species was declared extirpated.  Many partners, including Conservation Authorities and several NGOs, have undertaken projects to improve fish passage for this species while also benefiting other fish.  Projects completed over the past two decades include bypass channels, culvert baffles, dam removal, dam notching and fishway construction. This presentation will provide the status of fish passage connectivity in this important species recovery program.

Kendra Vorenkamp¹, Joseph Atkinson¹, and Sean Bennett²

¹Department of Civil, Structural, and Environmental Engineering, SUNY University at Buffalo, NY, USA

² Department of Geography, SUNY University at Buffalo, NY, USA

Laboratory experiments are described to evaluate schooling effects on swimming ability for Emerald Shiners (Notropis athernoides) to determine an appropriate water velocity for a design to allow fish passage across an identified velocity barrier in the Niagara River near Buffalo, New York. Emerald Shiners are a small-bodied schooling fish that are found throughout the United States and are prey to many sport fish and migratory birds. Habitat connectivity is necessary for population and ecosystem sustainability. Utilizing swim tunnels placed in a recirculating flume, schools of different numbers of fish were subjected to ramp critical velocity (U_crit) tests and endurance tests. The school sizes tested were 1 (individual control), 5, 10, and 20. The average U_crit as schooling fish fatigued was normalized to the relative proportion of the school, i.e. the average value for the 4th fish to fatigue within a school of five was compared to the 16th in a school of 20. In general, individual fish were found to be able to swim faster for longer periods of time as school size increased. For example, the final fish to fatigue in a school of 20 was observed to have an average critical velocity of approximately 75 cm s^-1, compared to ~50 cm s^-1 (school of 1), ~55 cm s^-1 (school of 5), and ~65 cm s^-1 (school of 10). The endurance tests resulted in an increased projected sustainable swimming success when compared to individually swimming fish. If velocity-barrier fishways incorporated space for fish to school, the design water velocity can be higher, reducing the cost of projects, with the potential for higher rate-of-passage success.

Megan Iun¹, David West² and Bruce MacVicar¹

¹University of Waterloo, Waterloo, Canada

²Ecofish Research Ltd, Vancouver, Canada

In this study, we partner with a First Nations community to restore spawning habitat for a threatened population of Chinook salmon on Vancouver Island (BC). Gravel enhancement has been identified as a process-based restoration technique with the potential to improve ecological functions such as fish spawning productivity, but such efforts are susceptible to infilling with fine sediment, armoring, scour, or inadequate upwelling or downwelling currents if incorrectly designed. Lake outlets are perceived to be ideal locations for spawning gravel placement for Chinook habitat restoration as Chinook salmon tend to spawn downstream of lakes and the upstream lake can trap sediment and buffer flashy floods. However, most published literature and existing gravel placement design guidelines focus on fluvial environments with bedload supply. Lake outlets are subject to different hydraulic and sediment conditions due to the gradual acceleration of flow along the stream so existing guidelines need to be tested and adapted for these environments.

We investigate the hydraulic design requirements for a gravel placement at a lake outlet. Using a Telemac-2D hydrodynamic model, we characterize the distribution of shear stress through the reach under a variety of flow and placement conditions to identify likely regions of fines flushing and gravel erosion. Field data is used to calibrate the model at low flow (Q = 10.2 m³/s) and higher flow conditions (Q = 123 m³/s). We found that the use of a single roughness parameter was insufficient to characterize the reach due to the spatial variation in bed material, flow depth in the transition zone between lake and stream, and the roughness effects of overhanging bank vegetation at high flow.

These results show that lake outlets can be represented by relatively simple 2D models but also highlight the importance of the collection of hydraulic characterization data. In the future, sediment tracking data and model results will be used to create maps of the mobility of different fractions of sediment to guide the placement of spawning gravels. Further research is required to explore the mobility conditions suitable for spawning habitat and the effects of bioturbation on critical shear stresses.

Josie Mielhausen¹, Jaclyn Cockburn², Paul Villard³ and André-Marcel Baril¹

¹GeoProcess Research Associates, Ottawa, Canada

²University of Guelph, Guelph, Canada

³GEO Morphix Ltd., Campbellville, Canada

Urban development in the Greater Toronto Area (GTA) impacts river systems and associated aquatic ecosystems, particularly by modifying flow mechanics and sediment dynamics. Additionally, in-stream structures (e.g., dams) cause habitat fragmentation and disrupt longitudinal connectivity for riverine species. To maintain fluvial geomorphological connectivity and aquatic ecological function (i.e., fish passage) in ecosystems impacted by urban development, river restoration is required. Rock weirs are one of the most commonly constructed nature-like fishways and are used in river restoration to provide physical channel stability, habitat enhancement, and unique hydromechanics offering fish passage opportunities. In 2017, a modified rock weir system was constructed in Weslie Creek, a small-scale watercourse in Aurora, Ontario, occupied by small-bodied fish species. To quantify fish passage suitability, profile and cross-sectional geometries were measured, and velocity measurements were collected at 10 rock weirs and 11 adjacent pool features. Velocities through rock weir gap and over-weir flow pathways were compared to the burst swim speeds of the local fish species, and fish ‘passability’ was determined. An assessment of rock weir structure was also completed to identify critical design considerations for enhancing fish passage. Results concluded that the modified rock weirs at Weslie Creek provided suitable passage for small-bodied fish species through gap and over-weir flow pathways, particularly during low water level conditions. Further, design considerations based on rock weir gradient, rock weir width, keystone size, and pool length, contributed to 100% fish ‘passability’ under all water level conditions. Methodology is provided for predicting small-bodied fish passage suitability through VRWs, informing best practices for VRW design and construction while balancing the requirements for channel stability and fish passage, and contributing to fish population management strategies.

Alex Meeker and Nigel Finney

Conservation Halton, Burlington, Canada

Since 2016, Conservation Halton has been working with its partners to restore sections of the East branch of Sixteen Mile Creek in the Town of Milton’s Drumquin Park.  Through this multi-year investment in green infrastructure within the Halton watershed, the project will restore the natural functions of the creek, improve the quality of fish habitat, remove instream fish barriers and increase biodiversity in the floodplain.

The first two phases of the project were completed in 2018 and 2021 while Phases 3 and 4 are in the detailed design stages with construction planned for 2025-2026.  Overall the project will result in:

• The removal of two outdated concrete weirs
• 810 linear metres of natural channel design
• 66 hectares of floodplain forest created and
• 1 hectares of floodplain wetlands.

Enhancements to instream conditions are designed to enhance aquatic habitat for Silver shiner and American eel, both species at risk.  This restoration initiative significantly enhances the climate resiliency of watercourse and the surrounding community while setting an example of multi-agency collaboration.

John Tweedie¹, Paul Villard¹, Bill Snodgrass² and Gerard Sullivan³

¹GEO Morphix Ltd., Campbellville, Canada

²City of Toronto, Toronto, Canada

³The Regional Municipality of York, Newmarket, Canada

In urban settings, natural channel designs must often balance various objectives relating to items such as channel stability, fish passage, or future maintenance requirements, while working within the fiscal and physical constraints of the system. Vortex rock weirs are a relatively recent design element that has been implemented in various natural channel designs throughout the City of Toronto and York Region. These features can enhance channel stability in relatively steep and confined streams, while also preserving and improving overall fish passage during both low and high flow conditions. The design and application of these elements have evolved since their introduction to further enhance geomorphological and functionality in light of novel research and case studies. A retrospective case-study assessment of past and current vortex rock weir applications in the City of Toronto and York Region was undertaken to describe the progression of the design and implementation, and to identify the strengths and limitations of the features in practice. Evaluations were predicated on hydraulic modelling, fish passage modelling, detailed field surveys, and long-term observations.

Paul Villard

GEO Morphix Ltd., Campbellville, Ontario, Canada

Optimizing characteristics of the floodplain and channel to meet specific ecological or physical targets is fraught with difficulty. It can produce systems that are unstable and inappropriate for a given sediment or hydraulic regime. It may also provide habitat niches under a narrow spectrum of natural variability over time. We often assume that we can optimize habitat for single species or ecological communities, especially where they previously existed. If impacts to the system are local and the system can be returned to its original or similar geomorphological, sedimentological, and hydrological condition, then restoring for specific species or ecological communities may be possible. However, these conditions are often not met, especially when sediment or hydrological regimes have been significantly altered. This approach can also result in stringent design targets that are not meaningful over the long-term. Such as, optimizing wetland designs to an average seasonal water depth and ignoring natural variability in hydrological regimes over time. This results in unbalanced and homogenous designs that are sub-optimal under a broad spectrum of potential natural conditions. A better approach is to balance ecological targets with the provision of the greatest level of physical variability. To create a system that has the resilience to maintain ecological integrity in the long run, we need to consider increased design variability. Hydrology and hydraulic models are employed to illustrate how this more balanced approach can provide corridor designs that are optimal during a greater range of potential conditions.