Keep chemicals that contain nitrates, or have the potential to generate nitrates, out of the water. Consider eliminating fertilizer use and replacing with organic farming methods: in Switzerland, for instance, farmers receive subsidies to eliminate their use of fertilizer. Alternatively, map fertilizer use specifically to treat only agricultural areas where it is particularly needed, in precise doses.
Control leaching of nitrates from septic systems into groundwater. Handle waste disposal systems properly to minimize the discharge of waste into groundwater. Alternatively, treat waste to remove nutrients.
Reduce vehicle emissions of NO and NO2, which have the potential to produce nitrates. Vehicle emission reduction is a multifaceted process, involving improving engine design, more precise fuel metering, precise ignition timing and reducing exhaust toxicity.