Tuesday, October 19, 2010

Four main pollutants in farm run off

Pollutant
Why it is a problem
Source of pollutant
How it gets to water
Nitrogen
  • It feeds nuisance plant and algae growth in waterways
  • Algae and nuisance plants affect stream life, block water intakes and drains, and make water unpleasant for swimming and drinking
  • Ammonia can be toxic to fish
  • Urine from stock
  • Nitrogen in fertiliser
  • Ammonia in dairy shed wastewater
  • It moves down through soil (leaching) into ground water and subsurface drains, which feed into streams
  • Surface runoff
  • Stock in streams
  • Discharges from oxidation ponds
Phosphorus
  • It feeds nuisance plant and algae growth in waterways
  • Algae and nuisance plants affect stream life, block water intakes and drains, and make water unpleasant for swimming and drinking
  • Dung from stock
  • Phosphate in fertiliser
  • Farm dairy effluent
  • Soil sediment
  • Soil and bank erosion (phosphate binds to soil particles)
  • Surface runoff
  • Discharges from oxidation ponds
  • Stock in streams
  • Subsurface drains
Sediment
  • It makes water murky and affects stream life
  • Poor water clarity makes water unsafe for swimming
  • Hillside erosion
  • Stream bank erosion and trampling
  • Tracks and races
  • Surface of paddocks
  • Surface runoff
  • Stream bank collapse
  • Hillside erosion
Faecal matter
(bacteria, viruses)
  • It creates a human health risk from swimming and drinking
  • It can affect stock health if present in stock water
  • Dung from stock
  • Farm dairy effluent
  • Stock in streams
  • Subsurface drains
  • Discharges from oxidation ponds
  • Surface runoff
  • Poorly-managed effluent irrigation


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