The main target of the present study has been to make the definitive design of the network of nitrate control in the aquifers of the Ebro basin, to give fulfillment to Directive 91/676/CEE, relative to the protection of waters against the contamination produced by nitrates of agrarian origin, and that was transposed to our ordering through R.D. 261/1996. This Directive presents between its main targets to reduce this contamination in groundwaters, as well as to act of preventive way to avoid that in the future this contamination progresses.