If rivers are a nation's lifeblood, the US should be on the sick list. More than half of the country's streams and rivers are in a "poor condition" for aquatic life, according to a survey by the US Environmental Protection Agency.
The agency sampled nearly 2000 sites in 2008 and 2009, looking at factors such as physical disturbances, mercury in fish flesh, faecal bacteria and nutrients from fertilisers.
Nutrient pollution, which causes algal blooms that can deplete a river's oxygen, was the main problem: 40 per cent of rivers and streams were rated "poor" for their high levels of phosphorus and 28 per cent were given the same rating for excessive nitrate contamination .... http://www.newscientist.com
