To evaluate the usefulness of ERTS imagery for obtaining information on snow cover for small mountain watersheds, two specific objectives were set: (1) to determine if snowpack ablation due to chinooks can be detected on ERTS imagery, and (2) to determine if melting snow can be distinguished from snow that has not yet begun to melt. The length of ERTS return period and the frequency of cloud cover over the mountains in winter combined to make the ERTS system almost useless in studying transient phenomena of short-return period such as the chinook. Melting snow could be distinguished from snow that had not reached melting temperature. The latter appeared light toned on both visible and near-infrared imagery because of its high reflectivity in these portions of the spectrum. Melting snow, however, appeared dark on near-infrared imagery because much of the incident infrared radiation is absorbed by the thin film of water on the surface of the melting snow.