Measurements of solute concentrations from previously unstudied watersheds throughout west Siberia suggest that warming and permafrost degradation will likely amplify the transport of dissolved solids to the Kara Sea and adjacent Arctic Ocean. We present concentrations of Ca²⁺, K⁺, Mg²⁺, Na⁺, Si, Cl⁻, SO₄²⁻, HCO₃⁻, inferred alkalinity, and total inorganic solutes (TIS) from 94 streams and rivers within the Ob'‐Irtysh, Nadym, and Pur river drainage basins. The sampled sites span ∼10⁶ km², a large climatic gradient (∼55°–68°N), and 39 permafrost‐influenced and 55 permafrost‐free watersheds. The solute composition of our samples is strongly influenced by carbonate mineral dissolution. Furthermore, our results show that TIS concentrations of waters in permafrost‐free watersheds average ∼289 mg L⁻¹, in contrast to only ∼48 mg L⁻¹ in permafrost‐influenced watersheds. This sixfold difference likely …