We compiled a 38 year dataset (1972 to 2010) to evaluate changes in water chemistry over time in relation to oil sands mining activities. We examined patterns in three focal elements (dissolved selenium, dissolved arsenic, total vanadium) at 96 sites along seven tributaries of the Athabasca and Clearwater Rivers. Concentrations of the three focal elements did not differ between sites sampled upstream versus downstream of future development, between sites upstream versus downstream of the primary bitumen-bearing geologic formation, or at an upstream site over a 33 year period on the Muskeg River (1976–2009).