Water in lakes, rivers and the oceans is being negatively affected by agricultural and lawn chemicals. Nitrogen and phosphorus rich fertilizers and herbicides or pesticides wash into the water supply and cause overgrowth of algae. The algae use up available nitrogen and phosphorus or other nutrients in the water and then die in large quantities, decomposition by bacteria then uses available oxygen supplies in the water. Lack of oxygen in the area where the excess growth of algae had occurred then harms over marine life. Some types of algae may also produce toxins which directly can harm marine life and sometimes humans also if the toxin is present in a source of water that is being used for drinking water. Treatment facilities normally remove a variety of substances from water that is intended for drinking water but unknown algal toxins may not be removed by the standard treatment methods. Phosphorus use in agricultural chemicals also removes it from the traditional cycle of growth and decomposition. When old vegetation or farm or human waste is decomposed and then used as fertilizer it returns phosphorus and nitrogen to the farm field for the next year's harvest of crops instead of allowing it to be added to lakes or oceans. More information about changes that could help make agriculture more sustainable for the future and the current water supply is available in a report, see the link in the following article: "Transforming Food Systems: Today's Realities and Tomorrow's Challenges," Inter Press Service . The impact of agricultural practices on the oceans is discussed in the first World Ocean Review. More recent reports cover aspects of ocean health and resources in more detail. The World Ocean Review provides summary and in depth reports on the oceans and coastal regions, fishing, and mineral resources, and impact by climate change and human use. WorldOceanReview.com . More information about algae overgrowth is available in chapter 2 How the Sea Serves Us of the World Ocean Review 4. /Disclaimer: This information is provided for educational purposes within the guidelines of fair use.