Water samples were taken from the Rio Blanco oil shale project retort 1 site approximately three- and one-half years after the shutdown of the oil recovery phase. Intermittent flooding and pumpdown of the retort occurred in the interval between shutdown and sampling for this study. Waters from within the retort and from downgradient and offsite locations were compared using a battery of analyses for inorganic and general water quality parameters. Inorganic solute species were selected as potential key indicator species if the particular species concentration inside the retort was greater than that outside the retort. Six inorganic parameters were found to qualify as potential key indicators for retort water migration from the site: potassium, lithium, ammonia, fluoride, thiosulfate, and boron. Except for ammonia, these indicators differ from those selected by other researchers at other modified in situ retorting sites. Ion chromatographic techniques were shown to be applicable for five of the six potential key indicators - all except boron which was detected spectroscopically. Low part-per-billion ion chromatographic analyses were demonstrated for lithium and ammonia. Fractional part-per-million ion chromatographic analyses were demonstrated for potassium and fluoride. Thiosulfate detection limits were in the low part-per-million range and only allowed detection of this indicator inside the retort. Five of the indicators (all except thiosulfate) were detected at slightly elevated levels in the Mahogany Zone ''B''groove completion of the downgradient well. However, insufficient historical baseline data are available at the low detection levels required to allow positive identification of communication between this well and the retort. The potential for enhancement of sensitivity of the ion chromatographic methods beyond that already achieved for the selected indicators is discusses. 11 refs., 1 fig., 9 tabs.