We use water for a variety of purposes from agricultural, domestic and industrial uses. This has involved activities that alter surrounding ecosystems, such as drainage, diversion of water for irrigation, industrial and domestic use, contaminating water with excess nutrient run-off (e.g. from fertilizers) and industrial waste, building damns, etc.

In May 2010, the UN produced the 3rd Global Biodiversity Outlook report. In it, the report notes that “shallow-water wetlands such as marshes, swamps and shallow lakes have declined significantly in many parts of the world.” (p.42).

The report also notes that water quality in freshwater ecosystems is an important biodiversity indicator, yet global data is quite lacking. But there are numerous examples that are known. Quoting a number of examples from the report,

  • Between 56% and 65% of inland water systems suitable for use in intensive agriculture in Europe and North America had been drained by 1985. The respective figures for Asia and South America were 27% and 6%.
  • 73% of marshes in northern Greece have been drained since 1930.
  • 60% of the original wetland area of Spain has been lost.
  • The Mesopotamian marshes of Iraq lost more than 90% of their original extent between the 1970s and 2002, following a massive and systematic drainage project. Following the fall of the former Iraqi regime in 2003 many drainage structures have been dismantled, and the marshes were reflooded to approximately 58% of their former extent by the end of 2006, with a significant recovery of marsh vegetation.
  • More than 40% of the global river discharge is now intercepted by large dams and one-third of sediment destined for the coastal zones no longer arrives. These large-scale disruptions have had a major impact on fish migration, freshwater biodiversity more generally and the services it provides. They also have a significant influence on biodiversity in terrestrial, coastal and marine ecosystems.

The report also notes that “The number of observed ‘dead zones’, coastal sea areas where water oxygen levels have dropped too low to support most marine life, has roughly doubled each decade since the 1960s. Many are concentrated near the estuaries of major rivers, and result from the buildup of nutrients, largely carried from inland agricultural areas where fertilizers are washed into watercourses. The nutrients promote the growth of algae that die and decompose on the seabed, depleting the water of oxygen and threatening fisheries, livelihoods and tourism.” (p. 60)