An integrated process for removing sulfate from water sources, such as pretreated acid mine drainage (AMD). The multivalent cation (MVC) content of a sulfate stream is reduced by strong acid cation (SAC) ion exchange and sulfate is concentrated with a membrane system and separated as precipitate and overflow. Precipitation results from reaction of sulfate with MVC produced by regeneration of SAC with sodium chloride. The overflow is reacted with carbonate to precipitate MVC, generate sodium chloride and give a further overflow stream. This latter stream is concentrated to a level capable of being a regenerant for the SAC and when needed, used to regenerate the SAC and produce MVC for sulfate precipitation. The process minimizes the use of chemicals by treating, reconcentrating and recycling input species. Capital expenditures are minimized by precipitation of only side streams.