CONAMA Resolution 396/08

CONAMA Resolution 396, April 3, 2008
Published in Official Gazette 66 on April 7, 2008, Section 1, pages 64-68
Establishes provisions related to the classification and environmental guidelines for the framework of groundwater and makes other provisions.

THE NATIONAL ENVIRONMENT COUNCIL – CONAMA, in accordance with the power bestowed upon the Council by art. 8, item VII of Law 6.938 from August 31, 1981, and in accordance with its Internal Regulations and the contents of Process 02000.003671/2005- 71, and,

Considering that ground waters are considered by art. 26 of the Federal Constitution as a National public good;

Considering that Law 6.938 from Aug. 31, 1981 is aimed at the safeguarding, preservation, improvement and recuperation of environmental quality through the rationalization of its use, the control and zoning of potentially polluting activities and the establishment of national environmental standards;

Considering that Law 9.433 from Jan. 8, 1997, which instituted the National Water Resource Policy and in particular its articles 9 and 10 which set provisions for the classification framework of water bodies, ratifies that it is the duty of environmental legislation to establish water body classes in order to fulfill the framework of water resources according to their preponderant usage;

Considering that Resolution 12 from July 19, 2000 issued by the National Water Resources Council (CNRH) determines that it is the duty of the Water or Basin Agencies , within their area of competence, to propose the framework of water bodies divided into classes to the respective Hydrographic Basin Committees, according to their preponderant usage;

Considering that Resolution 15 from Jan. 11, 2001 issued by the CNRH, establishes that the division of water body framework into classes will follow the hydrogeological characteristics of aquifers and their preponderant usage and demands their specific definitions;

Considering the need to integrate the National Policies related to Environmental Management, Water Resource Management and the use and occupation of land in order to safeguard the social, economic and environmental function of groundwaters;

Considering that aquifers are present in different hydrogeological contexts which may surpass the limits of hydrographic basins and that groundwaters possess intrinsically different physical, chemical and biological characteristics and that is necessary to classify them according to their particularities;

Considering that the classification of groundwaters is essential for the establishment of quality references in order to allow their division into classes;

Considering that the framework sets the attainment of final goals, may set intermediary and progressive goals, mandatory, aimed at is effectivisation;

Considering that the prevention and control of pollution are directly connected to the usage and classification of water quality demanded for a given groundwater body;

Considering the need to promote the protection of groundwater quality and that, when polluted, their recuperation is slow and expensive, decides:

Art. 1 This resolution Regulates the classification and environmental directives for the framework, prevention and control of pollution of groundwaters.


Art. 2 The following definitions are hereby adopted for all purposes of this Resolution:

I – groundwaters: natural or artificial waters located in the subsoil;
II – toxicological analysis: chemical or biochemical analysis undertaken in order to determine toxic compounds, its biotransformation products or their effects upon biological substances of potentially exposed organisms;
III – aquifer: hydrogeological body with the capacity to accumulate and convey water through its pores, fissures or spaces that are the result of the dissolution and entrainment of rock materials;
IV – quality class: group of water conditions and standards that are needed for the fulfillment of preponderant usage, current and future;
V – classification: qualification of groundwaters according to quality standards which allow for the establishment of their framework;
VI – quality condition: the quality of groundwater, at a given moment, in relation to the requirements related to its usage;
VII – framework effectivisation: attainment of the final framework;
VIII – framework: setting of a water quality goal or objective, reached or upheld in one aquifer, group or parts of aquifers in accordance with their intended preponderant use, current and future;
IX – Method Detection Limit (MDL): the smallest amount of concentration of a substance that can be detected, but not necessarily quantified, through the used method;
X – Practical Quantitation Limit (PQL): smallest concentration of a substance whose quantity can be determined with precision and exactness through the used method;
XI – Sample Quantitation Limit (SQL): PQL adjusted to the specific sample characteristics;
XII – goals: physical undertakings and management activities in accordance with the measuring units and pre-established schedules, mandatory;
XIII – monitoring: measuring or verification of quality or quantity parameters of groundwaters, through a defined frequency;
XIV – quality standard: limit rate adopted as a normative requirement for water quality parameters, based on quality reference rates and maximum rates allowed for each of the preponderant uses;
XV – water quality parameter: substances or other indicators that represent water quality;
XVI – remediation: technique or group of techniques present in groundwaters;
XVII – toxic tests: tests undertaken with specific organisms (animals, plants, microorganisms or cell cultures) under standardized conditions which allow for the establishment of possible adverse effects of the assessed sample;
XVIII – preponderant uses: main uses for underground waters which include human consumption, animal drinking irrigation and recreation;
XIX – Quality Reference Value (QRV): concentration or value of a parameter unit that defines the natural quality of groundwater; and
XX – Maximum Allowable Value (MAV): maximum rate allowed for one parameter, specific for each of the uses of groundwaters.


Art. 3 Groundwaters are classified as:

I – Special Class: aquifers, group of aquifers or part of these destined for the preservation of ecosystems in integral protection conservation units and which contribute directly to surface water stretches categorized as special class water bodies;
II – Class 1: aquifer water, group of aquifers or part of these, with no anthropic related changes, and which do not demand any kind of treatment for any of its preponderant uses due to natural hydro-geochemical properties;
III – Class 2: aquifer water, group of aquifers or part of these, with no anthropic related changes, but may demand adequate treatment depending on its preponderant use and due to its natural hydro-geochemical properties;
IV – Class 3: aquifer water, group of aquifers or part of these, with anthropic related changes, do not require any kind of treatment due to these changes but may demand adequate treatment depending on its preponderant use and due to its natural hydro-geochemical properties;
V – Class 4: aquifer water, group of aquifers or part of these, changed through anthropic activities and can only be used , without treatment, for less restrictive preponderant uses; and
VI – Class 5: aquifer water, group of aquifers or part of these which may have been changed through anthropic activities and can only be used for uses that do not depend on water quality.


Art. 4 The Maximum Allowable Values (MAVs) for the respective use of groundwaters must be followed when the water is used, with or without treatment, independently of class framework.

Art. 5 Special class groundwaters must keep their natural quality specifications.

Art. 6 The establishment of standards for Classes 1 to 4 must be based on Quality Reference Values determined by competent organs and on the Maximum Allowable Values for each preponderant usage, in compliance with the Practical Quantification Limits listed in Annex I.

Single paragraph. Parameters that present Practical Maximum Values for one sole use will be valid for other uses, when specific PMVs have not been established by the competent organ.

Art. 7 Class 1 groundwaters present, for all parameters, Quality Reference Values under or equal to the Maximum Allowable Values which are more restrictive for preponderant uses.

Art. 8 Class 2 groundwaters present at least one of the parameters, Quality Reference Value that is superior to the Maximum Allowable Value more Restrictive -MAVr+ preponderant uses.

Art. 9 Class 3 groundwaters must follow the Maximum Allowable Value more Restrictive -MAVr+ among its preponderant uses, except when it is the natural condition of the water.

Art. 10. Class 4 groundwaters must follow the Maximum Allowable Value less Restrictive -MAVr- among its preponderant uses, for each of the parameters, except when it is the natural condition of the water.

Art. 11. Class 5 groundwaters do not possess conditions and quality standards according to the criteria used by this Resolution.

Art. 12. The parameters that will be selected in order to substantiate a proposal for the division of groundwaters into classes must be chosen in function of their preponderant uses, hydrogeological hydro-geochemical characteristics, pollution sources and other technical criteria defined by the competent organ.

Single paragraph. Among the selected parameters the following should, as a minimum, be considered, Total Dissolved Solids, nitrate and thermotolerant coliforms.

Art. 13. The competent organs must monitor the necessary parameters in order to follow–up on the condition of groundwater quality, based on parameter selection according to art. 12, as well as pH, turbidity, electrical conductivity and water level measurement.

§1 The initial monitoring frequency must be at least every six months and defined according to the hydrogeological and hydro-geochemical characteristics of the aquifers, pollution sources and intended usage and may be reassessed after a representative period.

§2 The competent organs must undertake, every five years, a characterization of the water quality that takes into account all parameters listed in annex I as well as other that may deemed necessary.

§3 Monitoring results must be statistically analyzed and measurement uncertainties must be taken into account.

§4 The assessment of groundwater quality must be complemented , when professionally justified, through toxic tests on appropriate organisms for each of the uses or through toxicological adequate analysis.

§5 Should the undertaking of the studies mentioned in the previous paragraph become necessary due to the activities of identifiable entrepreneurs, the expenses for the same will be carried by the entrepreneurs.

Art. 14. Independently of any of the maximum rates allowed for Class 3 and 4, any increase in the concentration of contaminants must be monitored, their origin identified and adequate prevention and control measures implemented by the competent organs.

Art. 15. The samples and analysis of groundwaters and their interpretation for the assessment of quality conditions will be undertaken by the competent organ through the use of their own laboratory or associated or contracted laboratories.

Art. 16. The samples and analysis of groundwaters must be undertaken by laboratories or institutions that possess quality criteria and procedures that have been approved by the organs responsible for the monitoring activities.

Art. 17. In order to comply with the provisions set by this Resolution, samples, analysis and quality control aimed at the characterization and monitoring of groundwaters must adopt the following minimum procedures:

I – groundwater samples must be collected through the use of standardized methods and taken from sample locations that are representative of the area of interest;
II – if samples are taken from tubular and monitoring wells these must be constructed according to current accepted standards and techniques;
III – analysis must be undertaken through the use of integral samples, without filtration or any other type of alteration, except for preservatives which, when necessary, must follow current technical standards;
IV – the analysis mentioned in item III, when technically justified, must also be taken from the dissolved fraction;
V –physiochemical analysis must be undertaken through the use of standardized methods and in laboratories that meet the practical quantification limits listed in Annex I of this Resolution;
VI – if a substance appears in concentration levels that are below the limits of practical quantification they will be considered as absent for all purposes of this Resolution.
VII – if the sample quantification limit is above the practical quantification limit this will also be accepted for all purposes of this Resolution as long as it can be technically justified; and
VIII – if the substance has been identifies in the sample as being between the LDM and the LGA the fact must be reported through the analytical report including the note that the concentration cannot be determined with reliability and does not present, in this case, non-conformity in relation to the MAVs defined for each class.

Art. 18. Analysis results should be reported through analytical reports that include, at least:

I – identification of the sample location, date and time of sample collection entry in the laboratory, and the chain of sample custody;
II – information regarding the analysis method that has been used for each analyzed parameter;
III – quantification limits practiced by the laboratory, when applicable, for each of the analyzed parameters;
IV – results of method blanks and surrogate results:
V – measurement uncertainties for each parameter; and
VI – additional tests and recovery of matrix analyses (spike).

Single paragraph. Other documentation such as control charts, chromatograms and results obtained by proficiency tests may be requested at any time by the competent environmental organ.

Art. 19. Competent organs may impose additional quality conditions and standards for aquifer waters, group of aquifers or part of these or make them more restrictive, conditioned to local conditions, through professional foundations as well as establish restrictions and additional measures of exceptional or temporary character.


Art. 20. The environmental organs in cooperation with water resource management organs must promote the implementation of Aquifer Protection Areas and Perimeters for the Protection of Supply Wells aimed at the protection of groundwater quality.

Art. 21. Environmental organs, in cooperation with health and water resource managers must promote the implementation of Groundwater Usage Restriction and Control Areas, as exceptional and temporary measures undertaken due to quality and quantity conditions of groundwater resources and when they are required in order to restrict the use or the collection of water in order to protect aquifers, human health and ecosystems.

Single paragraph. The water resource, health and environment management organs must cooperate in order to define restrictions and measures for the control of the use of groundwaters.

Art. 22. The class restrictions and demands related to the framework of groundwaters, approved by the competent water resource council, must be observed during environmental licensing processes, economic-geological zoning processes and in relation to the implementation of other environmental management tools.

Art. 23. Artificial refilling and injection in order to contain the salt rates of Class 1, 2, 3 and 4 aquifers, group of aquifers or part of the same, cannot lead to alterations in the quality of groundwaters that may restrict their preponderant usage.

Art. 24. Injections into aquifers, group of aquifers or parts of the same aimed at remediation must be controlled by competent organs in order to uphold intended objectives and reach and uphold the quality standards for their preponderant usage and in order to prevent any risks to the environment.

Single paragraph. The injection that is the subject of the heading of this article cannot be undertaken in order change the water quality in aquifers, groups of aquifers or parts of the same, adjacent or sub adjacent unless it is aimed at quality improvement.

Art. 25. Aquifers, group of aquifers or parts of the same that are subjected to refilling or injection, according to the specifications of articles 21 and 22, should be the object of the implementation of a specific groundwater quality monitoring program.

Art. 26. Aquifers, group of aquifers or parts of the same that hold Class 5 waters can be subjected to direct injection under the control of competent organs and based on hydrogeological studies presented by the interested party which prove, though monitoring practices, that the injection will not affect the quality conditions in relation to the adjacent and sub adjacent groundwater framework.

Art. 27. The affectation and release of effluents and wastes onto the soil must follow the criteria and demands defined by the competent organs and may not add any type of characteristics to groundwaters that are not in harmony with their framework.

§1 The affectation and releases mentioned in the heading will not be allowed in cases when the waters of aquifers, groups of aquifers or parts of the same are characterized as Special Class waters.

§2 Affectation and release procedures must be preceded by specific plans and programs for the monitoring of groundwater quality conditions and approved by the competent organ.


Art. 28. The framework of groundwaters must follow the standards and procedures defined by the National Water Resource Council (CNHR) and State Water Resource Councils as well as the directives that will be presented in this chapter.

Single paragraph. According to the provisions set by this Resolution the framework for groundwaters into classes will be undertaken based on its most restrictive, actual or intended, preponderant uses with the exception of Class 4 groundwaters which will be classified according to its less restrictive usage.

Art. 29. The framework for groundwaters will be undertaken by aquifer, groups of aquifers or parts of the same, at the same depth point of extraction for its preponderant uses, and must follow these minimum demands:

I – hydrogeological and hydro-geochemical characterization;
II – vulnerability assessments and pollution risks;
III – registration of existing and operational wells;
IV – current and previous soil use and occupation;
V – technical and economic framework viabilization;
VI – identification of potentially polluting sources; and
VII – natural quality and the quality condition of groundwaters.

Art. 30 Aquifers, groups of aquifers and parts of the same which show that the quality of water is not in harmony with the standards demanded for class framework must be subjected to environmental control actions in order to improve the quality of the waters to their respective class, with the exception of substances that exceed the established limits due to their natural properties.

§1 The environmental control actions mentioned in the heading of this article must be undertaken in function of the framework goals, intermediary goals can be established.

§2 The gradual improvement of water quality and harmonization with the standards demanded for the respective class must be defined considering the available remediation technologies, economic viability and current and future soil and groundwater usage and must be approved by the competent environmental organ.

§3 If it is not possible to undertake the harmonization foreseen in the previous paragraph the re-classification framework of groundwaters must be undertaken through specific studies.

§4 Measures aimed at the containment of groundwaters must be enforced by the competent organ whenever technically justifiable.

Art. 31. Studies related to the framework of groundwaters must observe the hydraulic interconnection with surface waters in order to allow for the harmonization of the respective framework proposals.

Art. 32. Groundwaters that possess Total Dissolved Solid rates that surpass 15.000 mg/L, in aquifers, groups of aquifers or parts of the same, are constrained to Class 5 framework classification.


Art. 33. The framework class of groundwaters, as well as their quality properties, must be published periodically by the competent organs through quality reports and signs placed at monitoring locations.

Art. 34. The Maximum Allowed Values and the Practical Quantitation Values, included in Annex I, must be re-evaluated every five years or less when technically justified.

Single paragraph. The competent management organs may, at any given time, include other uses for groundwaters or add non-listed substances and define their Maximum Allowed Values and Practical Quantification Values, whenever technically justified.

Art. 35. Studies should be promoted in order to define Maximum Allowable Values that are in harmony with national conditions, in particular in respect to animal drinking and irrigation waters.

Art. 36. Competent organs must undertake radiochemical characterization of groundwaters in regions that are not subjected to radioactive effects.

Art. 37. This Resolution shall enter into effect on the date of its publication.

MARINA SILVA – Council President

This text does not substitute the text published in the Official Gazette on April 7, 2008.