Hydroelectricity provides 6% of U.S. electrical power needs, but hydro-dams also cause environmental harm, including the retardation or complete blockage of spawning runs of anadromous fishes. To facilitate fish movements, engineered-fishways have long been used but many have performed poorly. Dam-removal is the most effective way of restoring dwindling migratory fish populations by allowing unrestricted pathways to their spawning areas and for the downstream migrations of post-spawning adults and juveniles. However, removals of hydro-dams result in a loss of electricity production. For the replacement of energy foregone from hydro-dam removals, various alternative energy installations are now feasible. We present one-to-one conceptual replacement of hydropower with photovoltaic outputs for large and small river systems in Maine. We estimate that the equivalent land area needed to replace the dams with PV panels in the Kennebec River watershed—producing an annual mean±(SE) of 1101.7±37.9GWh—is 950.7±32.8ha, which is equivalent to 22% of the existing reservoir area. For the Mousam River, three hydro-dams dams could be replaced with 0.38 ha of PV. Our results indicate that modest land areas are needed to replace hydroelectricity with PV from even heavily dammed rivers, providing a realistic and potentially highly effective conservation policy option for Maine and for elsewhere.