The Alden fish-friendly turbine was originally designed for new hydro projects or powerhouse additions with heads between about 6 and 30 m and unit flow of about 15 to 70 cms. More recently, the Alden turbine has been considered for application at large dams with heads of about 30 m or greater and turbine flows of more than 200 cms. A new retrofit design of the Alden turbine has also been developed to replace a Francis runner at a small hydro project in the USA. Large dam applications were considered on a conceptual level and indicated that the Alden turbine has potential to be installed at existing and new projects on large river systems like the Columbia River in the USA and Mekong River in Southeast Asia. Efficiencies of these large units are expected to be comparable to more conventional turbine designs (e.g., Kaplan and Francis), whereas survival rates are expected to be considerably higher (greater than 99% for fish with lengths up to 425 mm). Compared to the original Alden design, the re-design was developed to increase turbine efficiency and generation while providing a safe passage route for downstream migrating fish at a low head dam. It was demonstrated that the re-design would increase average annual energy production by 4.3% based on current flow allocations for generation, downstream passage routes, and bypass reach habitat. Survival of fish exposed to blade strike and low pressures is predicted to increase dramatically, from 96.0% to 99.8% for 100-mm fish and from 83.0% to 99.8% for 300 mm fish. The results of the conceptual analysis for large dams and the re-design for a small hydro project demonstrate the ability to apply the Alden turbine at a wide range of projects to provide a safe passage route for downstream migrants without compromising generation output.