As part of the Ulaanbaatar Metro Project, surface water samples were collected along the proposed metro alignment and laboratory analyses were conducted to preliminarily assess environmental impacts and establish baseline data for future monitoring. The analysis was carried out in accordance with relevant standards and methodologies במסגרת the preparation of the Detailed Environmental Impact Assessment (DEIA) report.

Although the Selbe and Uliastai rivers are located near the project area, the metro construction works will not directly intersect with these rivers. However, there is a potential risk of impact on groundwater during deep excavation works; therefore, detailed drainage and groundwater protection systems have been carefully planned.

This analysis not only identifies the current condition of water quality but also serves as essential baseline data to monitor potential changes during project implementation.

          On-site Measurement Results – Uliastai River

Analysis Information

• Date: April 21, 2025
• Laboratory: Water Analysis Laboratory, Institute of Geography and Geoecology, Mongolian Academy of Sciences
• Sampling Organization: Econature LLC

Conclusion:

• Very Fresh Water: The river water has low mineralization and retains its natural purity, classified as “very fresh”.
• Soft Water: Chemically, the water contains low levels of calcium and magnesium, making it very soft, with no hardness or scale-forming properties.
• Compliance with Standards: The pH level and six key parameters fully meet the Mongolian standard (MNS 4586:2004), confirming the absence of chemical contamination.
• Clarity: The water has normal color and odor. Except for slight natural turbidity during spring and autumn high-flow periods, the overall water quality is very good.

ANALYSIS RESULT

          On-site Measurement Results – Selbe River

Conclusion:

• Fresh Water: The total dissolved solids (TDS) level of the river water is twice lower than the permissible limit, classifying it as “fresh water.” This indicates that the natural purity of the water has been preserved.
• Soft Water: The chemical composition of the water falls within the soft water category, meaning it does not cause scaling or sediment buildup in pipelines and engineering structures, indicating good quality.
• Compliance with Standards: The pH level and six key parameters fully comply with the Mongolian standard (MNS 4586:2004), with no evidence of chemical or industrial contamination.
• Clarity: The water has normal color and odor. Although slight turbidity may occur during spring and autumn due to soil runoff, this does not negatively affect the chemical quality of the water.

ANALYSIS RESULT

          On-site Measurement Results – Tolgoit River

Conclusion:

• High Mineralization: The electrical conductivity (EC) and total dissolved solids (TDS) levels exceed the established standards. This indicates elevated mineral content, likely due to local soil characteristics or human activities.
• Water Hardness: The chemical composition falls within the moderately hard category, indicating a higher mineral content compared to the Uliastai and Selbe rivers. 
• Clarity and Color: The water shows low transparency (turbidity) and a grayish coloration, both exceeding standard limits. Minor sediment presence was also observed.
• pH Level: The water has a pH of 7.65, which is within the normal (neutral) range and is considered a positive indicator.

ANALYSIS RESULT

Implementation Approach During the Project:

By establishing a detailed baseline of water quality prior to the commencement of construction, a monitoring framework is being put in place to ensure that river water quality is not degraded and that pollution is prevented throughout the project implementation.

During the implementation of the metro project, environmental management measures will be applied and regular monitoring will be carried out to maintain the current good quality of the Uliastai and Selbe rivers, and to prevent any further deterioration of the water quality of the Tolgoit River.