While there are limited theoretical benefits associated with repowering older hydroelectric facilities, these benefits do not withstand serious scrutiny when assessed through the lens of climate resilience, ecological integrity and sustainability, dam-safety obligations, and long-term system reliability. Ontario’s legacy hydro fleet—particularly facilities under 10 MW share common structural, hydrological, and environmental constraints that make repowering neither cost-effective nor aligned with modern electricity system needs.
These facilities rely on shallow, warming headponds highly vulnerable to drought, erratic inflows, and extreme precipitation events, producing increasingly unreliable and unpredictable generation. Their reservoirs continue to emit methane from decades of sediment accumulation, degrade water quality, and lack fish passage, perpetuating habitat fragmentation and cumulative watershed harm.
For these reasons, excluding facilities under 10 MW from repowering eligibility is both reasonable and evidence-based. Hydrologically and structurally, these aging dams experience worsening inflow volatility, growing climate-risk exposure, and escalating regulatory obligations, making repowering economically irrational once full sediment, safety, and environmental requirements are applied.