The project goal is to have a diagnosis of water quality of a transboundary river that receives contributions from municipal wastewater with or without treatment, as well as water for agricultural returns that can affect water quality in the Lower Rio Grande, then water quality model. The project is supported with Conagua-Conacyt Sector Funds.
The goal was covered done in the dry season four samples at 15 sites in the main river channel, two tributaries (river Alamo and San Juan), five agricultural drains and 10 discharge of wastewater, including effluent treatment plants located in the section from the dam downstream of Falcon International to the mouth of the Rio Grande to the Gulf of Mexico. About 80 chemical and microbiological parameters, including regulations (NOM-001-SEMARNAT-1996) for wastewater discharges to receiving body and pesticides in the river and tributaries were analyzed.
The Lower Rio Grande is classified as a water body Type B with urban public use so that concentrations obtained from the physico-chemical, microbiological parameters, pesticides and heavy metals were compared with the guidelines of water quality for use 1 set out in the Federal law.
The results indicated that river dissolved oxygen in all cases values greater than 4 mgL-1 were presented considered suitable for use 1 and protection of aquatic life. While total dissolved solids total phosphorus and sulfur, everywhere river and tributaries exceeded the guideline. In April 2016 discharges of effluent treatment plants in Ciudad Mier, Ciudad Camargo and Reynosa 2 did not meet the maximum allowable limit (MAL) of 75 mgL-1 BOD and 200 mgL-1 of COD; Fats and Oils plant Miguel Aleman and Camargo (MAL 15 mgL-1); Fecal coliform plants Nuevo Guerrero, Camargo and Reynosa 2 (1000 MPN/100 mL). The contribution of organic matter, measured as BOD ranged from 1.9 to 36 ton/day. No pesticides were detected.
The results allow zoning of the main sections of the river that receive inputs of pollutants such as El Anhelo Dren where necessary management actions to control pollution because it receives the discharge of the WWTP Reynosa 1 and Escondida Lagoon and that through a monitoring program and surveillance actions to be implemented to improve treatment systems or failing properly operate them to always comply with the regulations. Management must include the participation of the United States, to assess their discharges because the American side have seven treatment plants that discharge to the Lower River Bravo/Grande.