BOD₅ and ammonium are the main indicators used to characterize organic pollution in water. BOD₅ reflects the amount of dissolved oxygen required for the aerobic decomposition of organic matter present in water. High concentrations of these indicators often signal organic pollution and can have a dangerous impact on water deoxidation, increased concentration of ammonium, and the disappearance of fish and invertebrates.

The primary sources of organic matter in Armenia are domestic and industrial wastewater (untreated or insufficiently treated), which are discharged directly into rivers due to the lack of treatment plants. Runoff from agricultural areas is also a source of pollution.

From 2010 to 2024, the average concentrations of BOD₅ and ammonium at observation points increased by 35% and 52%, respectively.

The Hrazdan River is one of the longest and most polluted rivers in Armenia. The impact of the absence of a wastewater treatment plant is especially evident at the 55th observation point, which is the first observation point after Yerevan (the capital of Armenia, population about 1 million) and reflects the urban wastewater impact of the city on the river. This circumstance strongly influences the averaged time series, especially for ammonium. During 2010–2024, the average ammonium concentration at observation points below settlements—including the 55th point—was 1.4–2.0 times higher than in the same period when the 55th point was excluded.

2024 annual average concentration classes by RA WBMAs 

BOD5	Ammonium

Note: Water quality classes determined by BOD₅ (left) and ammonium (right) based on the average annual concentrations of river observation points in 2024. The maps were provided by the "Hydrometeorology and Monitoring Center" SNCO of the Ministry of Environment of the RA. The national assessment system was applied. For information on the relevant national standards, see the indicator description in the “National Target” section. The assessment system is the same as that used for the EEA indicator WAT 002 – Oxygen-consuming substances in European rivers.

The maps were provided by the "Hydrometeorology and Monitoring Center" SNCO of the Ministry of Environment of the RA.

Note: Water quality classes determined by BOD₅ (left) and ammonium (right) based on the moderate annual concentrations of river observation points in 2024. The maps were provided by the "Hydrometeorology and Monitoring Center" SNCO of the Ministry of Environment of the RA. The national assessment system was applied. For information on the relevant national standards, see the indicator description in the “National Target” section. The assessment system is the same as that used for the EEA indicator WAT 002 – Oxygen-consuming substances in European rivers.

The proportion of water quality classes at the observation points in 2024, determined by BOD₅, is as follows:

•    Northern WBMA: 100% “good”
•    Akhuryan WBMA: 20% “high”, 60% “good”, 20% “moderate”
•    Hrazdan WBMA: 38% “high”, 50% “good”, 12% “poor”
•    Sevan WBMA: 50% “high”, 50% “good”
•    Ararat WBMA: 50% “high”, 50% “good”
•    Southern WBMA: 67% “high”, 33% “good”

The proportion of water quality classes at the observation points in 2024, determined by ammonium, is as follows:

•    Northern WBMA: 33% “good”, 50% “moderate”, 17% “bad”
•    Akhuryan WBMA: 20% “moderate”, 20% “poor”, 60% “bad”
•    Hrazdan WBMA: 50% “high”, 25% “good”, 25% “bad”
•    Sevan WBMA: 67% “high”, 8% “good”, 17% “moderate”, 8% “bad”
•    Ararat WBMA: 50% “high”, 50% “good”
•    Southern WBMA: 33% “high”, 50% “moderate”, 17% “bad”

Indicator definition

C-10 indicator - Oxygen content in river water, the indicators of which are BOD₅ (the amount of dissolved oxygen necessary for aerobic decomposition of organic matter in water) and ammonium nitrogen.

Units

BOD₅: mgO2/l,
Ammonium: mgN/l.

Justification for indicator selection

A high concentration of organic matter (bacteria and decomposing organic waste) can increase the pollution level of river water, disturb the balance of aquatic ecosystems, and reduce biodiversity, which negatively affects water quality.

References

• Council Directive 91/271/EEC of 21 May 1991 concerning urban wastewater treatment
• Directive 2000/60/EC of the European Parliament and the Council of 23 October 2000 establishing a framework for Community action in the field of water policy
• Water Framework Directive
• UNECE, 2018.  Guidelines for the Application of Environmental Indicators, Description of C10. Biochemical oxygen  (BOD) and concentration of ammonium in rivers.
• UNECE, 2018.  Guidelines for the Application of Environmental Indicators, Glossary of terms – C10. Biochemical oxygen demand (BOD) and concentration of ammonium in rivers.

Context description

National policy context

• Republic of Armenia Water Code (adopted on 4 June, 2002)

The Water Code regulates water relations concerning the use, protection, and development of water resources to ensure a guaranteed, adequate, and safe water supply for the population, protect the environment, and promote the rational development of the country’s water fund.

• N75-Ն RA Government Resolution (adopted on 27 January, 2011)

"On establishing standards for ensuring water quality in each water basin management area, depending on the specifics of the location.” This resolution sets water quality standards for each water basin management area, taking into account the specific characteristics of the location.

International policy context
The UNECE–WHO/European Protocol on Water and Health aims to protect human health and well-being through sustainable water management and by preventing and controlling water-related diseases. It provides a framework for the translation human rights to water and sanitation into practice, as well as for the implementation of SDG 6. Although the Protocol was signed in 1999, its ratification is still ongoing and has not yet been finalized.

Targets

National targets

Standards according to N75-Ն RA Government Resolution

International targets
The UN Sustainable Development Goal 6 target 6.3 aims to achieve improved water quality by 2030 through reducing pollution, eliminating waste, and minimizing the release of hazardous chemicals and materials. It also seeks to halve the proportion of untreated wastewater and substantially increase the recycling and safe reuse of water globally.

Methodology for indicator calculation

The monitoring programme is designed to take into account the spatial and seasonal dynamics of the indicators. Monitoring sites are located both above and below settlements, which provides information on background concentrations as well as on settlement-related impacts. The number of river observation points is 45 (21 above and 24 below settlements), representing 22 rivers. The data are provided by the “Hydrometeorology and Monitoring Center” SNCO of the Ministry of Environment of the RA. For each observation point, the annual average concentrations of BOD₅ and ammonium are calculated based on the arithmetic mean of the monitoring data obtained during the year. Separate averages are calculated for river observation points above and below settlements

Gap-filling methodology

For the analysis of time series and their trends, only complete series are used (i.e., there are no missing values in the site data set). This ensures the consistency of the averaged data sets. Thus, there was no need to apply a gap-filling methodology.

Methodology references

• EEA, 2005. EEA core set of indicators guide. EEA Technical report No 1/2005, ISBN 92-9167-757-4, Luxembourg.
• ISO 7150-1:1984 Water quality — Determination of ammonium — Part 1: Manual spectrometric method. The procedure is applicable to the analysis of potable water, and most raw and waste waters. Application to excessively coloured or saline waters shall be preceded by distillation.
• ISO 5815-2: 2003 Environmental protection and environmental management. Analytical control and monitoring. Water quality. Determination of biochemical oxygen consumption after n days (BODn). Part 2. Method without diluting samples.
• UNECE, 2018. Guidelines for the Application of Environmental Indicators, Description of C10. Biochemical oxygen demand (BOD) and concentration of ammonium in rivers.
• UNECE, 2018. Guidelines for the Application of Environmental Indicators, Glossary of terms – C10. Biochemical oxygen demand (BOD) and concentration of ammonium in rivers.
• UNSD and UNEP, 2013. Questionnaire 2013 on Environment Statistics. United Nations Statistics Division and United Nations Environment Programme, Questionnaire 2013 on Environment Statistics, Section Water.

Methodology uncertainty
No methodological uncertainty was identified.

Data sets uncertainty
No uncertainty was identified.

Rationale uncertainties
Biochemical oxygen demand and ammonium are indicators that characterize water pollution related to oxygen consumption. However, their annual average values do not always fully represent the actual situation, as they do not capture seasonal fluctuations.

• ArmStatBank

River water quality indicators by observation points and years.
Data on BOD₅ and ammonium concentrations in surface water are available and stored in the national database of the “Hydrometeorology and Monitoring Center” SNCO of the Ministry of Environment of the RA.

• Report on the State of Environment

Water quality assessments (according to national water quality standards) are published by the “Hydrometeorology and Monitoring Center” SNCO of the Ministry of Environment of the RA.