Technical Abstract: Although fecal-oral transmission of avian influenza viruses (AIV) via contaminated water represents a recognized mechanism for transmission within wild waterfowl populations, little is known about viral persistence in this medium. In order to provide initial data on persistence of H5 and H7 AIVs in water, we evaluated eight wild type LPAI H5 and H7 viruses isolated from species representing the two major influenza reservoirs (Anseriformes and Charadriiformes). In addition, the persistence of two HPAI H5N1 viruses from Asia was examined to provide some insight into the potential for these viruses to be transmitted and maintained in the environments of wild bird populations. Viruses were tested at two temperatures (17 C and 28C) and three salinity levels (0, 15, 30 parts per thousand sea salt). The wild-type H5 and H7 AIV persistence data to date indicate that: 1) H5 and H7 AIVs can persist for extended periods of time in water, with a duration of infectivity comparable to AIVs of other subtypes; 2) the persistence of H5 and H7 AIVs is inversely proportional to temperature and salinity of water; and 3) a significant interaction exists between the effects of temperature and salinity on the persistence of AIV. Results from the two highly pathogenic avian influenza H5N1 viruses from Asia indicate that these viruses did not persist as long as the wild-type AIVs.