Density of troglobitic crustaceans and levels of potential food sources were compared in reference pools and pools disturbed by septic system effluent in Banners Corner Cave, Russell Co., Virginia. Data from six physicochemical parameters indicate slight to high disturbance in five pools in reference to two undisturbed sites. Disturbed sites had high levels of conductivity, nutrients, and fecal coliforms. Highly disturbed sites had large decreases in concentration of dissolved oxygen. Isopod (Caecidotea recurvata) and amphipod (Stygobromus mackini) density and isopod size-class distributions were measured seasonally with short-term mark-recapture techniques. Isopods were absent only in highly disturbed sites. Highest isopod density (up to 74.6/m²) occurred in slightly and moderately disturbed sites. Amphipods were absent from all disturbed sites. Fungal biomass, total organic matter (TOM), and bacterial biomass in pool sediments were measured to determine changes in food availability caused by the septic system effluent. Fungal biomass was negligible in all pools. Contribution of bacterial biomass to sediment TOM was increased in disturbed pools with little overall increase in TOM. Bacteria, fine particulate matter and coarse particulate matter (CPOM) were used equally well in laboratory growth experiments. Presence of CPOM, not organic enrichment by septic system outfall, is the most likely cause of high isopod density in some pools. Septic system effluent may provide additional food to the aquatic community in Banners Corner Cave, but generally was damaging to the system. / M.S.