Nitrogen and phosphate within manufactured fertilisers, and contained in farmyard manure and slurry, can cause severe problems when released into rivers and wetlands. Typically, there is an unbalanced growth of aquatic plants and algae known as eutrophication. This is harmful to both aquatic plants and animals and contaminates drinking water. Farms losing these plant nutrients to the environment are of course wasting money when they could be better used to improve productivity. The Island’s wildlife areas including designated Sites of Special Scientific Interest can be severely affected by eutrophication.
Sediment and Turbidity
Erosion and run-off of soil into rivers, lakes and ponds causes turbidity which blocks the penetration of light through the water. Plants and animals do not thrive under such conditions with fish gills becoming clogged and layers of silt can settle out which smothers wildlife. Water containing sediments intended for human consumption is also made more costly treat.
Microbial and parasitic contamination
Farm animal faecal matter can cause a significant risk to human health when people encounter contaminated river or bathing waters. Illness can also result when microbes and parasites get into drinking water. Typically, these harmful materials come from livestock with direct access to watercourses or from badly sited or maintained manure and slurry stores. There are also problems from unconsented discharges of human sewage.
Pesticides are of course intended to control unwanted plants and animals but, when lost to rivers and other wetlands, can kill wildlife. It is not unknown for a river to lose most of its animals when only small amounts of a pesticide have been allowed to escape from crop sprayers or poorly stored containers. People are also at risk should they meet water polluted with pesticide.