There are fish passage facilities (fish-ways) at each of the four Hydroelectric Dams on the lower Susquehanna River. Conowingo, Holtwood and Safe Harbor Dams, the first three moving upriver, have fish lifts or elevators. York Haven Dam, the fourth dam, has a vertical slot fish ladder. Fish lifts work by using water currents to attract the migrating fish into a channel. Crowder gates close to crowd the fish over the hopper bucket, and the bucket is lifted vertically to the level of the reservoir upstream. The water and fish in the bucket are then dumped into an exit trough which leads the fish to the reservoir.

All of the fish-ways were constructed with viewing windows where biologists count the migrating fish. Click here to see a movie clip of gizzard and American shad moving past the viewing window at Conowingo Dam, this is recorded, not live.

Further upstream, the Fabri-Dam at Sunbury is scheduled to have a fish ladder built when state funds become available. Hepburn Street Dam in Williamsport has a ladder in place, which will be upgraded in the near future.

Fish passage operations begin at Conowingo on April 1, or when water temperature reaches 50F. Fish passage operations upstream are triggered by counts of migrating fish at the next dam downstream. Reports of fish-way activity, numbers and species of fish passed are provided by the dam operators to the Fish and Boat Commission on a weekly basis and are updated regularly and reported on this website (see table below). Very high flow events can disrupt normal fish passage schedules and operations, however, by following the weekly updates, observers can get a feel for the beginning, peak and end of the run. Fish-way operations cease around mid-June to coincide with the apparent ending of the run. Declining numbers of fish counted and temperatures increasing to ranges above that of spawning shad trigger the closing of the fish-ways. Dam operators, the U. S. Fish and Wildlife Service and the Pennsylvania Fish and Boat Commission work together to determine fish-way schedules.