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STOCKHOLM ENVIRONMENT INSTITUTE
In 1998 the EPA adopted the Clean Water Action Plan, which stated that excessive nutrient pollution results in greater than expected growth of macrophytes or phytoplankton, and potentially harmful algae blooms or outbreaks leading to declining oxygen levels, an imbalance among aquatic species, public health risks, and a general degradation of the aquatic resource. The “Key Action” for addressing nutrient over-enrichment was a requirement that states develop and implement numeric limits on the amount of so-called “nutrients” – phosphorus and nitrogen – allowed in waterbodies by the year 2004.