Recommendations for legal discharge of wastewater to rivers, lakes and subsoil

By Santamarina Steta

Most economic activities require the discharge of wastewater. While in some cases it is possible to discharge into sewage systems, in others, wastewater must be discharged into rivers, lakes or directly into the subsoil, either because there is no sewage infrastructure or because the authorities that operate the sewage system do not allow it.

Unfortunately, poor management of wastewater discharges has caused some rivers and lakes to present high levels of contamination. As an example, in 2021, the National Water Commission (CONAGUA) monitored 788 rivers and lakes throughout the country, and around 300 reported some kind of contamination.

Water pollution is a worrying factor for everyone, as it generates various environmental and social conflicts. For this reason, CONAGUA has ordered the definitive closure of some projects and has imposed sanctions and the obligation to remediate those who generate discharges.

Considering the above, we recommend that those who discharge wastewater into rivers, lakes and subsoil consider the following points to ensure that their discharge is legal:

Have a discharge permit issued by CONAGUA.Whoever intends to discharge wastewater into rivers, lakes and subsoil must first obtain this permit. In this regard, the irrigation of green areas with wastewater is considered a discharge to the subsoil. Discharges without this permit may result in the imposition of fines and the closure of the activities that cause the discharge.

Avoid polluting discharges. It is necessary to have a water treatment plant in optimal conditions so that the wastewater to be discharged complies with the parameters established in NOM-001-SEMARNAT-1996. It is important to note that NOM-001-SEMARNAT-2021, which establishes stricter quality parameters, will enter into force in March 2023.

Presentar las declaraciones en el sistema DECLARAGUA y, en su caso, pagar derechos. Los titulares de un permiso de descarga deben informar a la CONAGUA la calidad y cantidad de las aguas residuales vertidas, así como pagar los derechos correspondientes. Si el titular demuestra que las sustancias en las descargas se encuentran dentro de los límites máximos permisibles establecidos en la norma oficial mexicana, quedará exento de dicha obligación de pago. Para ello, deberá presentar un análisis de calidad de las aguas residuales.

Ensure that the laboratory issuing the analysis is authorized by CONAGUA and accredited by the Mexican Accreditation Entity.If the laboratory does not have current accreditation and/or authorization, its analyses will be invalid and no fee exemption can be requested.

Do not exceed the permitted discharge volume.Discharging more water than authorized, even if it is not contaminated, could result in the imposition of sanctions.

Apply for a discharge permit based on projections and estimates of the wastewater to be discharged.In case of discrepancies in the declarations, CONAGUA may require payment of fees for the total volume permitted (regardless of whether a lower volume was actually discharged).

Avoid diluting wastewater discharges.This is considered a serious infraction that may result in the closure of the project. In addition, CONAGUA may require the payment of fees for the total volume established in the permit.

Request the extension of the permit at least 6 months before the end of its validity. Unlike other authorizations, which allow for requests for extensions at any time prior to their expiration, permit extensions must be requested at least 6 months prior to the expiration date.

Obtain a concession title to use river or lake riparian zones. The river or lake shore is considered a federal zone under the jurisdiction of CONAGUA. If the holder of a discharge permit intends to construct discharge facilities (such as ramps or pipelines) in this area, he must obtain a concession title from CONAGUA.

The care of rivers, lakes and groundwater is of utmost importance to ensure the ecological balance. In addition, this will preserve the water supply for human consumption and economic activities. In short, wastewater discharges into these ecosystems must be carried out responsibly and in full compliance with environmental regulations.