Energy Indicators for Sustainable Development: Guidelines and Methodologies International Atomic Energy Agency United Nations Department of Economic and Social Affairs International Energy Agency Eurostat European Environment Agency

METHODOLOGICAL DESCRIPTION 
(a) Underlying Definitions and Concepts: Water pollution from energy industries 
depends very much on the activity and the type of technology and abatement 
techniques used. Most important in this respect are the coal mining and oil extraction 
industries, but the use of energy in industry in general can lead to discharges of 
pollutants into water bodies. A range of by-products and residues are generated in 
energy production, including bottom ash, fluidised bed ash, fly ash and flue gas 
desulphurisation residues and by-products. Knowledge of the process and the 
pollutants likely to be generated is necessary when developing a programme for 
monitoring water quality. 
When measuring water quality, measurements can be made directly in effluent 
discharges or in the downstream watercourse as a measure of the environmental 
impact of the discharge. The following list presents typical monitoring requirements 
for energy industries: 
Flow Rate: Volume, measured in cubic metres per second, hour or day. Volumes can 
be multiplied by the concentration of the pollutant to calculate the mass emissions of 
individual pollutants. 
pH: This is a measure of the acidity/alkalinity of a discharge. The pH of a 
watercourse affects the solubility of various substances and alters the habitat for fish, 
animals and plants. 
Total Organic Carbon (TOC): Measured in milligrams per litre (this can be used as a 
surrogate for chemical oxygen demand [COD] or biochemical oxygen demand 
[BOD]). TOC measures the organic content in a discharge, which can sometimes be 
elevated when the discharge is contaminated. Elevated levels of organic matter 
change the natural balance of plants and organisms in the watercourse. 
Hydrocarbon Oil: Measured in milligrams per litre. Surface water drainage passing 
through industrial facilities and storage areas can often become contaminated with 
hydrocarbon oil, which can pollute watercourses and harm plants and animals 

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downstream. Contamination of fresh water with very low levels of oils makes the 
water undrinkable (see ENV4-2: Oil discharges into coastal waters). 
Suspended Solids: Measured in milligrams per litre. These can often contaminate 
watercourses downstream of storage areas or from mining/drilling operations. 
Suspended solids colour the water, change the opacity of the water and can smother 
plants and animals downstream. 
Ammoniacal and Total Nitrogen: Measured in milligrams per litre. Nitrogen is a 
nutrient, which often causes nutriphication of the watercourse, changing the habitat 
and affecting native species. 
Chloride and Sulphides: Measured in milligrams per litre. Wastewater from flue gas 
desulphurisation plants contains salts such as chloride and sulphides, which can be