Language selection


Terms of Reference

Risk to Fish from Very Low Head Turbine Installations

Regional Peer Review - Ontario and Prairie Region

December 5-6, 2023


Chairperson: Jon Midwood


One of the most significant concerns with hydroelectric power production is injury and mortality of fish passing through turbines during intentional or unintentional downstream passage (Algera et al. 2020). There are a number of mechanisms by which fish can become injured or killed as a result of passage (entrainment) through turbines as summarized by Čada (2001), including rapid and extreme pressure changes, cavitation, sheer stress, collision, turbulence, and grinding. As a result, developers have been working for decades toward developing turbines that incorporate features to make them less hazardous to entrained fishes (Fraser and Deschenes 2007, Foust et al. 2011). To determine whether or not a turbine is indeed “fish friendly”, not only does the rate of mortality need to be quantified, there is also a range of sublethal effects that must be considered (Ferguson et al. 2006). Current monitoring plans for a range of turbine types typically involve periodically walking downstream of the turbine to observe dead fish, and this level of monitoring may not yield reliable information as to the risk to fish.

Novel turbine technologies are being proposed at new and existing infrastructure (weirs, non-power dams), which still need to be assessed for their fish friendliness (Cooke et al. 2011) and Canadian application (NRCan 2018). Low head (< 15m) dams are being explored as viable hydropower options, which could add between 5-10 GW of power (Tung et al. 2007) or about 10% of Canada’s 82.3 GW of installed capacity (IHA 2022) to Canada’s energy mix. Very Low Head (VLH) turbine technology is a unique, cost-effective hydropower technology developed to address a head of < 5 meters and up to 500 kW of capacity. A recently constructed (2016) VLH turbine on the Severn River, ON, provided a unique site for the first study of this new technology in Canada. The VLH installation on the Severn River was supported by NRCan as a demonstration site to represent a clean and reliable low-impact source of electricity allowing for significant cost savings related to civil works due to its modularity concept.

DFO’s Fish and Fish Habitat Protection Program (FFHPP) is seeking science advice to determine if this technology can indeed be considered fish friendly for Canadian taxa and systems. Using acoustic telemetry, live fish passage, and sensors designed to record the conditions experienced by fish as they pass through turbines, DFO Science aimed to provide a direct quantification of the overall risk of entrainment, injury, and immediate or delayed mortality to the resident fish community at the Wasdell Falls (Severn River, Ontario) VLH turbine installation. The results of this work aim to provide science advice to FFHPP to better understand the fish friendliness of this technology and aid their reviews of other proposed VLH turbine installations.


  1. To determine the overall risk to the resident fish community from the VLH turbine installation at Wasdell Falls;
  2. To determine the level and type of monitoring required at future installations; and,
  3. Identify uncertainties and knowledge gaps, and if necessary, recommend additional information, research, monitoring, data collection, etc. that is required to further assess the potential impacts of VLH turbine installations on Canadian fish communities.

Expected Publications

Expected Participation



Participation to CSAS peer review meetings is by invitation only.

Date modified: