Abstract: A method to remediate a contaminated groundwater zone by shielding electron acceptors contained in groundwater flow that interfere with beneficial anaerobic reactions in the contaminated groundwater zone. Examples of such interfering electron acceptors include dissolved oxygen, nitrate, and sulfate. The method prevents electron acceptor-rich groundwater located upgradient from a contaminated zone from flowing into the contaminated groundwater zone. By diverting acceptor-rich groundwater around a contaminated zone, beneficial anaerobic reactions are enhanced that either biodegrade the contaminants, or change the subsurface geochemical environment so that contaminants are immobilized. Methods to establish a groundwater diversion system include constructing physical barriers to block clean groundwater flowing into a contamination zone, or creating a stagnant zone hydraulically by pumping clean groundwater upgradient of the contaminated zone or injecting clean water downgradient of the contaminated zone.