2.1.4.2. Human activities threatening to water quality

In Cambodia, land and water resources and their associated biota are considered to be major environmental concerns. Commercial forestry, agriculture and mining affect the country's surface water system along with the Mekong River upstream trans-boundary factors working through the regional surface water network and local rivers to affect the primary resources of the Tonle Sap Lake and its tributaries. Additionally, urban/town and industrial pollution sources, aquaculture, and mining contribute to water quality deterioration and affect the productivity of the inland fishery, which is also increasingly influenced by intensified commercial and artisanal fishing practices. Wastewater, sanitation and solid waste management are affecting the urban/town water environment as well.

The outcomes of analyses of water samples in 2001, 2002, and 2003, which were taken from designated sampling points in the Mekong River, Tonle Sap River, and Bassac River, have shown that these natural water sources are generally less polluted in comparison to other riparian countries. During the rainy season (July to October) the river water is turbid with a high concentration of silt resulting from soil erosion in the upstream and local catchment areas. Vice versa, in the dry season, especially in April, BOD values noticeably exceed water quality standards for public water areas set by the Ministry of Environment; coliform also increases from February to July.

Although water quality is still in good condition, with the high acceleration of industrial and related economic growth without transparent land-use planning, increased agro-chemical consumption, and urbanisation, water quality will deteriorate in the future unless proper wastewater management concepts are implemented and regularly followed up.

River water quality data from the Ministry of Environment has been available since 1999. The water quality indexes are compiled by the Ministry of Environment including pH, Conductivity, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Fecal Coliform, and Total Suspended Solids (TSS), NO2, NO3, and PO4. The following figures indicate water quality in watercourses with high concentration of Fecal Coliform for a few months in a year where population density is high, and is compared to the National Water Quality Standard of the Ministry of Environment (Fecal Coliform <5000).

Figure 1: Total fecal coliform at Chroy Changvar
(Mekong upstream) in 2004 (source: Ministry of Environment)

Figure 2: Total fecal coliform at Kien Svay
(Mekong downstream) in 2004 (Source: Ministry of Environment)

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Table of contents > 2. River Basins > 2.1. The Mekong River System (Basin)

2.1.1. Introduction

2.1.2. Mekong River tributaries and Rainfall

2.1.3. Detailed survey of rainfall and surface water in the Mekong catchment

2.1.4. Water environment in the Mekong River systems

2.1.4.1. Human activities threatening to water quantity

2.1.4.2. Human activities threatening to water quality

2.1.4.3. Case study on human factors threatening to the water environment

2.1.4.4. Transboundary issues