Type	Field	Possible Measures
Economic Costs	Fishing and commercial extraction	Output/volume decrease
		Lost revenues from recreational fishing
	Recreational facilities	Attendance decrease
		Loss in rent values
	Water purification	Treatment costs
		Inspection costs
	Accidents/Spills	Cleanup costs
Social Costs	Public Health	Health services costs
		Loss of life expectancy
Environmental Costs	Damage to ecosystems	Losses in biological diversity and sustainability
		Loss of water regeneration / purification by wetland

Externalities of Water Pollution

• Economic Costs. When a regional aquatic ecosystem is damaged, commercial fishing and aquaculture are likely to be less profitable. A comparison between average output of commercial activities, taking account of extraction means (ships, surface cultivated, etc.), over a time period may reveal some indicators about the economic costs of water pollution. Another dimension includes damage to recreational facilities, particularly around fresh water lakes. This can be evaluated by loss of attendance and in rent values. Water purification costs, including treatment and inspection, have taken a significant weight on municipal budgets. As water supply and demand are in urbanized regions, this externality is difficult to overcome. Securing reliable and uncontaminated sources for large cities requires heavy investment in infrastructure (dams, pumping stations, waterworks, treatment plants, etc.). Last but not least, accidental spills by tankers (petroleum products) are always expensive events to cleanup.
• Social Costs. Contaminated water is harmful to human beings, depending on the nature of the pollutants and the type of exposition. However, limited harm occurs in developed countries, notably because of public awareness and water treatment facilities. The problem takes a very different dimension in developing countries where limited water treatment is available and where the population relies more on outdoor water sources.
• Environmental Costs. Besides extensive damage to the aquatic ecosystems, limited attentions has been put upon losses in water regeneration and purification potentials by the fragmentation and/or removal of wetland by transportation infrastructure.