National Environmental (Ambient Water Quality) Regulations, No. 01 of 2019.

These Regulations are issued by the Minister of Environment and Natural Resources under the Section 23A of the National Environmental Act.
No person shall discharge, deposit or emit any pollutant into the inland surface waters to exceed the Ambient Water Quality Standards in relation to the categories specified in the Schedule of the Regulations. The Central Environmental Authority shall be responsible for the maintenance of the quality of inland surface waters in order to ensure compliance with the Standards specified in the Schedule.
Category A shall be water that requires simple treatment, for drinking ; Category B shall be bathing and contact recreational water ; Category C shall be water sutiable for aquatic life ; Category D shall be water source that require to undergo general treatment process, for drinking ; Category E shall be water suitable for irrigation and agricultural activities ; Category F shall be water with minimum quality but does not fall into categories A to E.