The Sub-Decree was established in compliance with Article 13 of the Law on Environmental Protection and Natural Resources Management. Based on its stipulation, the Ministry of Environment is responsible for preparing related water environment management/protection guidelines, which implemented by local authorities, including the provincial/municipal environmental departments.

The Sub-Decree focuses on the protection and conservation of water quality at public water areas, as well as the monitoring and controlling of any types of wastewater discharged from various pollution sources that do not have harmful impacts on water environment and aquatic life. In addition, the licensed owner/manager of factory and/or pollution source where his/her effluents were properly treated, and vice versa, he/she will be fined or punished if he/she has violated the Sub-Decree.

The Ministry of Environment determines to issue relevant declarations and directives to strengthen the effectiveness of implementation of the Sub-decree throughout the country.

The Sub-Decree on Water Pollution Control is comprised of eight chapters: (i) general provision; (ii) provisions on waste and hazardous waste discharge; (iii) effluent discharge permits; (iv) monitoring of pollution sources; (v) water pollution monitoring in public water areas; (vi) inspection procedure; (vii) penalty; and (viii) final provision.

The Sub-Decree generally focuses on the routine monitoring of water quality at public water areas and effluent, which discharged from industrial and other pollution sectors. The Sub-Decree mentioned that properly treated wastewater is based on the effluent standard. If the wastewater discharges into the public water areas without treatment, the Ministry of Environment will take action to fine the person(s) who violates the legal instruments. On other hand, the owner or manager of factories must ask for a permission towards the discharge of treated wastewater.

Additionally, the Sub-Decree includes the standards for :
(i) effluent standard for pollution sources discharging wastewater to public water areas or sewer;
(ii) type of pollution sources required having a permission from Ministry of Environment before discharging or transporting their wastewater;
(iii) Water Quality Standard in public water areas for bio-diversity conservation;
(iv) Water Quality Standard in public water areas for public health protection.

Effluent standard for pollution sources discharging wastewater to public water areas or sewer
The effluent standard for pollution sources discharging wastewater to public water areas or sewers was set up in order to control wastewater discharging from these sources. This is the first effluent standard of Cambodia of which has been put into effect and has been widely implemented throughout the countries. Different relevant -ministries, line agencies, NGOs, international organisations, private sector, and other related organisations have contributed to the development of activities in compliance with this standard. The standard was divided into categories of (i) discharging wastewater to public water areas; and (ii) discharging wastewater to sewers, because until today in cities and provinces, wastewater and industrial effluents are discharged into both receiving sources where easier

Table: Effluent standard for pollution sources discharging wastewater to public water areas or sewer access

Types of pollution sources required to have a permission from the Ministry of the Environment before discharging or transporting wastewater
The purpose of setting the regulation for discharging water is to monitor and control, especially, follow up the implementation of the environmental law by owners of these sources.

Table: Types of pollution sources required to have a permission from the Ministry of the Environment before discharging or transporting wastewater

Water quality standard in public water areas for biodiversity conservation
In Cambodia, some watercourses were used as a receiving source of treated/untreated wastewater or effluent, which discharged from various pollution sources. With this regard, the Water Quality Standard in public water area for bio-diversity conservation was separately divided into three main sources such as river, lake and reservoir, and coastal water. Experiences from many years ago indicated that some parameters were not included; therefore, it causes difficulty in assessing water quality in public water areas. Recognising the gap, the Ministry of Environment is ready to amend this Sub-Decree as necessary.

Table: Water quality standard in public water areas of biodiversity conservation

Water quality standard in public water areas for public health protection
The standard was attached in the Sub-Decree on Water Pollution Control aiming to control public water areas against any pollution, which had harmful effects on human health.

Table: Water quality standard in public water areas for public health protection