Consolidating the use of reclaimed water for irrigation and infiltration in a semi-arid agricultural valley in Mexico: water management experiences and results

The city of Ensenada (Baja California, Mexico) experiences severe water restrictions for urban and agriculture use, and reclaimed water (RW) for crop irrigation and aquifer infiltration has been identified as a promising water management option. This paper presents the path followed to consolidate the reclamation scheme that included monitoring programs on RW, groundwater, and agricultural soil. Seventy-nine percent of the RW samples complied with the particular discharge permit for El Naranjo wastewater treatment plant (WWTP), yet the local water utility has to have a better control of its wastewater treatment plant to avoid spikes of fecal coliforms. The presence of fecal coliforms in soil samples at surface and 30–60 cm depths indicates that farm workers could be at risk during the handling of the product, so it is highly recommended that workers be provided with clothes that will protect them from direct contact with water and soil. Results from monitoring wells adjacent to Las Ánimas and San Carlos creeks showed, on some occasions, the presence of fecal and total coliforms that could indicate infiltration of RW. In conclusion, technical aspects can be monitored and controlled yet the most challenging aspects that remain are social and political which require extensive negotiation and institutional arrangements.