Biodiversity of a river depends on the variation of nutrients, physico-chemical parameters and different biologically significant ion concentrations of the river water. Seasonal variation of nine biologically significant ion concentrations of Jalangi river water are reported in this article, month-wise, from April 2014 to March 2015. These ions, namely sodium, potassium, magnesium, calcium, carbonate, bicarbonate, nitrate, phosphate and chloride play vital role on the growth of aquatic flora and fauna present in the river. The average concentrations of arsenic(III), sulphate ion, fluoride ion, ferric ion and lead ions are also reported in this paper though are they are less significant. These data clearly helps to understand the background scenario of the river’s ecosystem.