Concentrations of trace elemental constituents in water draining an Eastern Ontario agriculture watershed have been determined using inductively-coupled plasma mass spectrometry. Water samples were collected in the Spring of 1991 from three locations. Unfiltered, 0.4 mum filtered as well as ultrafiltered fractions were analyzed. A total of 79 elemental isotopes ranging from Li-6 to Th-232 were utilized for analytical calibration to measure the concentrations of 38 trace and ultratrace inorganic elemental constituents. Estimates of concentrations were made for: Li, Be, B, Sc, V, Cr, Mn, Ni, Co, Cu, Zn, Ga, As, Br, Rb, Sr, Y, Mo, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Lu, Pb, Th and U. Typical levels found ranged from a mean of 0.05 mug/L for the rare earth elements to 330 mug/L for Sr. For the majority of elements, no differences in concentrations were evident between sampling locations or due to filtration. Exceptions were concentrations of Li, Mn and Pb which were affected by site, and Y which seemed affected by filtration. These quantitative baseline results will form the basis for selection and utilization of specific elements as tracers for modelling of water drainage and flow patterns. This mass spectrometric technique was demonstrated to be a capable, highly detective multielement method for trace element research of natural waters.