For fish and many species of molluscs, crustaceans, and insects, water is their only habitat. As agriculture is situated within watersheds, its practices often interface with watershed components and always have some effect. This effect may involve altering wildlife habitat and its ability to support a diverse biological community. Agricultural and other rural development activities often lead to land clearing, drainage, and straightening channels, which can alter the physical nature of waterways. Irrigation infrastructure often provides new aquatic habitat.
Excess nutrients cause eutrophication, which depletes oxygen.
Nitrogen and some pesticides may be lethal or sub-lethal to aquatic organisms when concentrations exceed threshold levels. Numerous conservation projects have been undertaken in Canada to restore and improve riparian and aquatic habitat, including work on wetlands and agricultural drains. Clean and useable waterways enhance the esthetic appeal of rural landscapes. Introduction Understanding the ecological issues that arise through the effects of agriculture on water is best achieved by stepping back and looking at the watershed as a whole. Water that falls in this basin as precipitation is collected, stored, released, and transported by a number of landscape components.