Las Arenitas is one of two wastewater treatment plants outside of Mexicali in Baja California that processes the city’s water to be reused for irrigation. Iban Leal is a chemist and the manager of the facility which is under the jurisdiction of CESPM, the state water commission. Water is pumped into the plant at a rate of 840 L per second and then travels through a series of ponds. This system of twelve shallow rectangular ponds help filter and clean the water through aeration, sunlight, chlorine and different types of bacteria.
From the ponds, the water flows into a 200-acre wetland. Edgar Carrera, a hydrologist and environmental engineer from the Sonoran Institute helps manage this area. The series of wetlands demonstrates a mutually beneficial partnership between the water treatment plant, the Sonoran Institute and the species that inhabit the marsh. The cattails that dominate the area filter out the chemicals left in the water and provide a home for over 150 species of waterfowl. Once the water has circulated through the wetland for several weeks, thirty percent is diverted towards the Río Hardy and the rest is pumped back into the Mexicali Valley for irrigation. Las Arenita’s wetland is also used for educational purposes. School groups from Mexicali come here to walk an interpretive trail built in partnership with the Sonoran Institute and learn about the project’s success.