The Environment Law establishes the authority of the Ministry of Environment and Natural Resources {"MARN") to ensure compliance with technical standards of environmental quality. These rules are contained, m general, in the Special Regulation of Technical Standards of Environmental Quality that implements the framework of guidelines and procedures to establish technical standards of environmental quality in receipt media, applicable specifically for discharges or emissions, in each of the areas, be it for the quality of air, fuel, noise, water and soil. 

By means of respect to water quality standards, it is important in any project or work, the aspects related to the discharge of wastewater, since the maximum permissible limits must met as a measure to prevent damage to the environment. The Special Regulation of Residual Waters establishes essential rules in order that the residual waters do not alter the quality of the receiving means {that is to say, any site, river, stream, lake, lagoon, spring, reservoir, sea, estuary, mangrove, swamp and other authorized sites where wastewater is discharged, excluding the sewage system) and protect the water resource from the effects of pollution. Therefore, any person who owns a work, project or actrvrty that produces or manages wastewater and discharges in a receiving environment, is obliged to install and operate treatment systems to comply with the provisions of this regulation and environmental regulations in general, including Salvadoran Standard NSO 13.49.01 · 09 "Wastewater Discharged to a Receiving Body" that establishes parameters and maximum perrmssibte values of wastewater. 

MARN, through Agreement No 277 (OD 149 Volume 416 of August 15, 2017), issued the new Categorization Criteria for Activities, Works or Projects whose purpose is to serve as orientation, reference and guidance on the classification of an activity, work or project.

Depending on the potential impact on the environment, the following categories are established PIAB is the category of actlvrtres. works or projects with low potential environmental impact and therefore does not require environmental documentation; P!AL are those with a mild potential environmental impact and PIAMA those that have a moderate or high impact. Another innovation is the evaluation given to the environmental criteria according to their level of significance assigning a value and establishing the following hierarchy: criteria of medium impact or CMI (criteria of lower value), criteria of high impact or CHI (criteria that have double the value of the MICs and is considered of greater relevance) and critical criteria or CC {due to their environmental importance they are assigned the maximum value). 

Regarding wastewater, this new categorization includes. within its general criteria, those associated with ordinary wastewater, establishing nine criteria of which seven are "CC" and two are "(Ml". Thus, for example, a CC cntenon is the discharge into stream, sea or the proposal of external that also implies that the project can be categorized as PIAL or PIAMA. 

In the case of the PIAMA projects (which require the preparation of an environmental impact study) the new General Terms of Reference for the Preparation of Environmental Impact Studies issued by the MARN {DO 152 Volume 416 of August 18, 2017), require that the studies include the teastbnity of handling and disposal of ordinary wastewater issued by the competent authonty, or a proposal for management and final disposal, which in any case is approved by the MARN. 

Authorities with competence m environmental matters are increasingly demonstrating their interest in verifying compliance with environmental regulations in general. through audits or inspections In these, the proper treatment of wastewater and compliance with the limits established by the standard are subject to revision. Therefore, it is important for companies to ensure that they have adequate wastewater treatment. which comply with these standards, in order to guarantee the continuity of their operations and operate under environmentally friendly production schemes.