Over two seasons, we observed passage of American eels (Anguilla rostrata) at an eelpassage facility (eel ladder) placed adjacent to an upland mill dam on a small tributary to theHudson River, New York. American eel use of the ladder was significantly correlated with freshetsand moon phase, similar to other studies of eel migration. Most of the migrants were young (,20cm total length). Several large American eels (.35 cm) exhibited local movements, including useof the ladder, as shown by recaptures of individuals marked with coded wire tags. Operation ofthe eel ladder greatly reduced the density of small American eels below the mill dam. Placing eelladders on upland obstructions has the potential to enhance the productivity of silver (sexuallymature) eels, an important consideration in the Hudson Valley, where hundreds of barriers havebeen constructed on upland tributaries.