4.7

• Sewage Pollution

  Waste matter that is rich in organic matter thus micro organisims thrive on it
• Domestic Waste 


  Sewage from rurual and urban carry many pathogenic microorganisims increasing content of nitrates and phosphorus in rivers
• Industiral processes

  Use of chemicals and processing heavy metals can result in the presance of metals in rivers like magnese mercury or copper
• Agricultural Pratices 


  Surplus of phospherous and nitrogen not absorbed by plants are washed from the land or percullate into ground water