Note:

- For parameters DDT, PCBs, organophosphorus pesticide, rely on the purposes of the monitoring program to select appropriate compounds to be monitored.

Table 2. Permissible limits of parameters in surface water to classify quality of water in rivers, streams, canals and ditches and to protect underwater habitats

Parameter

Water quality class

pH

BOD₅

(mg/L)

COD

...

...

...

TOC

(mg/L)

TSS

(mg/L)

DO

(mg/L)

Total Phosphorus
TP

 (mg/L)

Total nitrogen
TN

...

...

...

Total Coliforms

(CFU or MPN/100ml)

Heat-resistant coliforms
(CFU or MPN/100ml)

6,5 - 8,5

≤ 4

≤ 10

≤ 4

≤ 25

...

...

...

≤ 0,1

≤ 0,6

≤ 1.000

≤ 200

A

6,0 - 8,5

≤ 6

≤ 15

≤ 6

...

...

...

≥ 5,0

≤ 0,3

≤ 1,5

≤ 5.000

≤ 1.000

B

6,0 - 8,5

≤ 10

≤ 20

...

...

...

> 100 and Absence of floating trash

≥ 4,0

≤ 0,5

≤ 2,0

≤ 7.500

≤ 1.500

C

< 6,0 or  >8,5

> 10

...

...

...

> 8

> 100 and Presence of floating trash

≥ 2,0

> 0,5

> 2,0

> 7.500

> 1.500

D

...

...

...

Parameter

Water quality class

...

...

...

pH

BOD₅

(mg/L)

COD

(mg/L)

TOC

(mg/L)

TSS

...

...

...

DO

(mg/L)

Total Phosphorus
TP

(mg/L)

Total nitrogen
TN

(mg/L)

Chlorophyll-a

(mg/m³)

Coliform group

...

...

...

...

...

...

Heat-resistant coliforms
(CFU or MPN/100ml)

...

...

...

6,5-8,5

≤ 4

≤ 10

≤ 4

≤ 5

≥ 6,0

≤ 0,1

≤ 0,6

≤ 14

...

...

...

≤ 200

A

...

...

...

6,0-8,5

≤ 6

≤ 15

≤ 6

≤ 15

≥ 5,0

≤ 0,3

≤ 1,5

...

...

...

≤ 5.000

≤ 1.000

B

...

...

...

6,0-8,5

≤ 10

≤ 20

≤ 8

> 15 and Absence of floating trash

≥ 4,0

≤ 0,5

...

...

...

≤ 70

≤ 7.500

≤ 1.500

C

...

...

...

< 6,0 or >8,5

> 10

> 20

> 8

> 15 and Presence of floating trash

≥ 2,0

...

...

...

> 2,0

> 70

> 7.500

> 1.500

D

...

...

...

Note: Chlorophyll-a parameter is applied to environmental monitoring programs after 03 years from the date on which this Regulation is promulgated.

2.1. Interpretation of water quality classes:

Class A: Good quality. The concentration of dissolved oxygen (DO) present in aquatic ecosystems is high. Water may be used for domestic purposes, swimming or water recreation after appropriate treatment measures are applied.

Class B: Average quality. Aquatic ecosystems consume a lot of dissolved oxygen due to a large amount of pollutants. Water may be used for industrial or agricultural purposes after appropriate treatment measures are applied.

Class C: Poor quality. Aquatic ecosystems consume a lot of dissolved oxygen due to a large amount of pollutants. Water does not cause unpleasant odors and may be used for industrial purposes after appropriate treatment measures are applied.

...

...

...

2.2. Principles of assessing water quality according to Table 1

- Objectives of the water quality management plan and monitoring program serve as the basis for selecting parameters to be monitored in Table 1;

- Monitoring data used to assess quality of water in a river, stream, canal or ditch includes annual arithmetic mean of value measured at each representative measurement point with little local impact within a river, stream, canal or ditch with a minimum monitoring frequency of 06 times/year;

- Monitoring data used to assess quality of water in a river, stream, canal or ditch means the annual arithmetic mean of value measured at all monitoring points in such river, stream, canal or ditch with a minimum monitoring frequency of 06 times/year;

- Water quality at a measurement point is assessed as not meeting the goal of protecting human health if the annual arithmetic mean value of at least 1 parameter exceeds the limit specified in Table 1.

2.2. Principles of assessing and classifying water quality according to Table 2 or Table 3:

- Table 2 and Table 3 specify limits of parameters affecting aquatic life for the purpose of classifying water quality; serving as a basis for determining the goal of managing and improving water quality for parameters affecting aquatic life;

- Monitoring data used to assess and classify quality of water in a river, stream, canal or ditch under regulations in Table 2 includes annual arithmetic mean of value measured at each representative measurement point with little local impact within a river, stream, canal or ditch with a minimum monitoring frequency of 10 times/year;

- Monitoring data used to assess and classify quality of water in a lake, pond or lagoon according to Table 3 means the annual arithmetic mean of value measured at all monitoring points in such lake, pond or lagoon with a minimum monitoring frequency of 10 times/year;

...

...

...

- For saline-contaminated surface water areas, water quality shall be classified using the parameter TOC instead of the parameter COD;

- In case of monitoring the quality of surface water that is not contaminated with salinity, choose to monitor the parameter COD or TOC to classify water quality;

- The 4 water quality classifications are meant to improve water quality for parameters affecting aquatic life. To serve the purpose of assessing the concentrations of toxins affecting human health and ecosystems, depending on each area, it is necessary to select the parameters specified in Table 1 to carry out assessment.

2.4. Use of surface water for different purposes

- Organizations and individuals directly using surface water should pay attention to ensuring that the source of water used is treated to meet water quality standards by each purpose;

- In case of applying appropriate water treatment measures for each pollution parameter to ensure water quality standards by each purpose are met, the treated water may be used for purposes cleaner than those referred to in 2.1.

3. DETERMINATION METHODS

3.1. Monitoring methods intended for determining concentrations of parameters in surface water are specified under Table 4 or environmental monitoring techniques promulgated by the Ministry of Natural Resources and Environment.

Table 4. Methods for monitoring parameters in surface water

...

...

...

Parameter

Monitoring method, standard code

1

Sampling

TCVN 6663-6:2018;

TCVN 6663-1:2011;

TCVN 6663-3:2016

TCVN 6663-4:2018;

TCVN 5994:1995;

...

...

...

2

pH

TCVN 6492:2011

3

Dissolved Oxygen (DO)

TCVN 7325:2016;

SMEWW 4500O.C: 2017;

SMEWW 4500O.H: 2017

4

...

...

...

TCVN 6625:2000;

SMEWW 2540D:2017

5

COD

TCVN 6491:1999;

SMEWW 5220.B:2017;

SMEWW 5220.C:2017

6

BOD₅ (20ºC)

...

...

...

TCVN 6001-2:2008;

SMEWW 5210B:2017

7

Total Nitrogen (TN)

TCVN 6624:1-2000;

TCVN 6624:2-2000;

TCVN 6638:2000;

SMEWW 4500-N.C:2017

8

...

...

...

TCVN 6202:2008;

SMEWW 4500P.B&D:2017;

SMEWW 4500P.B&E:2017;

US EPA Method 365.3

9

Ammonium (NH₄⁺)

TCVN 6179-1:1996;

TCVN 6660:2000;

SMEWW 4500-NH3.B&D:2017;

...

...

...

SMEWW 4500-NH3.B&H:2017

10

Chloride (Cl^-)

TCVN 6194:1996;

TCVN 6494-1:2011;

SMEWW 4110B:2017;

SMEWW 4110C:2017;

SMEWW 4500.Cl-:2017;

US EPA Method 300.0

...

...

...

Fluoride (F^-)

TCVN 6195-1996;

TCVN 6494-1:2011;

SMEWW 4500-F-.B&C:2017;

SMEWW 4500-F-.B&D:2017;

SMEWW 4110B:2017;

SMEWW 4110C:2017;

US EPA Method 300.0

12

...

...

...

TCVN 6178:1996;

TCVN 6494-1:2011;

SMEWW 4500- NO^-₂.B:2017;

SMEWW 4110B:2017;

SMEWW 4110C:2017;

US EPA Method 300.0

13

Cyanide (CN^-)

TCVN 6181:1996;

...

...

...

SMEWW 4500-CN-.C&E:2017;

ISO 14403-2:2017

14

Arsenic (As)

TCVN 6626:2000;

ISO 15586:2003;

SMEWW 3114B:2017;

SMEWW 3114C:2017;

SMEWW 3113B:2017;

...

...

...

US EPA Method 200.7;

US EPA Method 200.8;

US EPA Method 6020B

15

Cadmium (Cd)

TCVN 6197:2008;

ISO 15586:2003;

SMEWW 3113B:2017;

SMEWW 3120B:2017;

...

...

...

US EPA Method 200.8;

US EPA Method 200.7;

US EPA Method 6020B

16

Lead (Plumbum) (Pb)

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3113B:2017;

SMEWW 3120B:2017;

...

...

...

SMEWW 3130B:2017;

US EPA Method 200.8;

US EPA Method 6020B

17

Total Chromium (Cr)

TCVN 6222:2008;

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3113B:2017;

...

...

...

SMEWW 3125B:2017;

US EPA Method 200.8;

US EPA Method 200.7;

US EPA Method 6020B

18

Chromium (6+) (Cr⁶⁺)

TCVN 7939:2008;

SMEWW 3500-Cr.B:2017

19

...

...

...

TCVN 6193:1996;

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3111B:2017;

SMEWW 3113B:2017;

SMEWW 3120B:2017;

SMEWW 3125B:2017;

US EPA Method 200.7;

US EPA Method 200.8;

...

...

...

20

Zinc (Zincum) (Zn)

TCVN 6193:1996;

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3111B:2017;

SMEWW 3113B:2017;

SMEWW 3120B:2017;

SMEWW 3125B:2017;

...

...

...

US EPA Method 200.8;

US EPA Method 6020B

21

Nickel (Ni)

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3111B:2017;

SMEWW 3113B:2017;

SMEWW 3120B:2017;

...

...

...

US EPA Method 200.7;

US EPA Method 200.8;

US EPA Method 6020B

22

Iron (Ferrum) (Fe)

TCVN 6177:1996;

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3500-Fe.B.2017;

...

...

...

SMEWW 3113B:2017;

SMEWW 3120B:2017;

US EPA Method 200.7;

US EPA Method 6020B

23

Mercury (Hydrargyrum) (Hg)

TCVN 7724:2007;

TCVN 7877:2008;

SMEWW 3112B:2017;

...

...

...

US EPA Method 200.8;

US EPA Method 7470A

24

Manganese (Mn)

TCVN 6002:1995;

TCVN 6665:2011;

ISO 15586:2003;

SMEWW 3111B:2017;

SMEWW 3113B:2017;

...

...

...

SMEWW 3125B:2017;

US EPA Method 200.7;

US EPA Method 200.8;

US EPA Method 6020B

25

Antimony (Sb)

SMEWW 3111.B:2017;

SMEWW 3113.B:2017;

SMEWW 3120.B:2017;

...

...

...

US EPA method 200.7;

US EPA method 200.8;

US EPA method 243.1

26

Anionic surfactant

TCVN 6622-1:2009;

SMEWW 5540 B&C:2017

27

Total oil and grease

...

...

...

SMEWW 5520B:2017;

SMEWW 5520C:2017

28

Total Phenols

TCVN 6216:1996;

SMEWW 5530 B&C:2017;

US EPA Method 420.1;

ISO 14402:1999

29

...

...

...

TCVN 6634:2000;

SMEWW 5310B:2017;

SMEWW 5310C:2017

30

Total DDT (1,1'-(2,2,2-Trichloroethane-1,1-diyl) bis(4-chlorobenzene) (C14H9Cl5)

TCVN 7876:2008;

TCVN 9241:2017;

SMEWW 6630B:2017;

SMEWW 6630C:2017;

...

...

...

US EPA Method 8270D;

US EPA Method 8270E

31

Lindane (C6H6Cl6)

32

Dieldrin (C12H8Cl6O)

33

Aldrin (C12H8Cl6)

34

...

...

...

(C10H5Cl7 & C10H5Cl7O)

35

Gross alpha activity α

TCVN 6053:2011;

TCVN 8879:2011;

SMEWW 7110B:2017

36

Gross beta activity β

TCVN 6219:2011;

...

...

...

SMEWW 7110B:2017

37

E.coli

TCVN 6187-2:1996;

SMEWW 9221B:2017;

SMEWW 9222B:2017

38

Total Coliforms

TCVN 6187-2:2020;

...

...

...

39

Heat-resistant coliforms

TCVN 6187-2:2020;

SMEWW 9221:2017

40

Polychlorinated biphenyls (PCBs)

TCVN 9241:2012;

SMEWW 6630C:2017;

US EPA Method 1668B;

...

...

...

US EPA Method 8270D

41

Tetrachloroethylene (C2Cl4) PCE

US EPA method 5021A

42

1,4-Dioxane (C4H8O2)

US EPA method 522

43

Carbon tetrachloride (CCl4)

...

...

...

44

1,2 Dichloroethane (C2H4Cl2)

US EPA method 502.2;

US EPA method 5021A;

US EPA Method 8260D

45

Methylene chloride (CH2Cl2)

US EPA method 432;

US EPA method 5021A;

...

...

...

46

Benzene (C6H6)

US EPA method 5021A

47

Chloroform (CHCl3)

US EPA method 551.1;

US EPA method 502.2;

US EPA method 5021A;

US EPA Method 8260D

...

...

...

Formaldehyde (CH2O)

US EPA method 8315A

49

Bis (2-ethylHexyl)phthalate (DEHP) (C24H38O4)

US EPA method 506

50

Organophosphorus pesticide

US EPA Method 8141B;

US EPA Method 8270D

...

...

...

Chlorophyll a

TCVN 6662:2000 (ISO 10260:1992)

3.2. Apart from the monitoring methods specified in 3.1, results from equipment for automatic and continuous monitoring of surface water that meets technical specifications as prescribed by law are acceptable.

4. REGULATORY REQUIREMENTS

4.1. Periodic or automatic and continuous monitoring of surface water quality and use of monitoring results for directly providing and disclosing information about environmental quality to the community must be performed by organizations that meet the requirements and conditions for environmental monitoring capacity according to the provisions of law.

4.2. Periodic monitoring of surface water quality shall be carried out according to monitoring goals to choose appropriate parameters to be monitored.

5. IMPLEMENTATION

5.1. Environment authorities shall provide guidance on, inspect and supervise the implementation of this Regulation.

5.2. In the cases where any of the legislative documents referred to in this Regulation is amended or replaced, the newest one shall apply.