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o c~ r-" ,::..... f\) c.o value (5 IlglL). These results indicated that the diets and possibly the feces and urine were indirectly adding selenium to the water. During the depuration period, waterborne selenium concentrations in all tanks were at or below 0.90 IlglL within II days, except for two replicates of treatment 2, Measured selenium concentrations in these replicate tanks were 1.55 and 5.65 /-lglL at day II of depuration and 0.95 and 1.25 1lg!L at day 25 of depuration. At 60 and 90 days of depuration, selenium concentrations in the replicate with 5,65 1lg!L at day II of depuration were at or below 0,75 1lg!L. Selenium concentrations in the other replicate tank of treatment 2 for the same periods were 0.20-0,30 IlglL. The reason for these high selenium values in two replicates of treatment 2 is not known, but it seems likely that there was reduced water flow from the diluter to these tanks during the first month of the depuration period. Water Quality Mean water quality characteristics in exposure tanks during the adult exposure were . .. within 10% of measured values in the blending tanks, except for alkalinity, chloride, and conductivity (Table I), The high chloride and conductivity values in the adult exposure water, compared to those in blending tanks, may be partly due to the dissolution of uneaten food as the diets were formulated to contain 2.57% NaCI by weight (T. Brown, BioProducts, personal communication). The reason for the reduced alkalinity in the adult tanks compared to the blending tanks is not known. Typically, DO concentrations decreased after feeding began and remained below the prefeeding concentrations until the tanks were siphoned and filtered. Mean (SD) concentrations of measured solids in adult exposure water were 19,8 (l0.3) mg!L for total suspended solids, 2.8 (6.6) mglL for fixed suspended solids, and 17.2 (10.6) for volatile suspended solids, Mean (SD) turbidity of the same water was 6,9 (3.7) NTU. These 26