A major concern in the development of in situ oil shale production has been the potentially adverse effects on water quality. The Laramie Energy Research Center (LERC) has monitored water quality at its oil shale research sites for the past several years. A summary and preliminary analysis of these data were made by Smith and Weand in 1977. This report updates the earlier effort for Rock Springs Sites 6 and 9, with consideration of the additional information collected in the interim.