BioGT: Watersheds, Water Pollution, and Land Use

Watersheds

• A watershed is the area of land where all runoff drains downhill to the same body of water

  • Runoff: rain or melting snow that runs across the surface of the land instead of sinking into the ground

• Runoff carries pollution throughout watersheds

Water Pollution

• Pollution

  • Something harmful added to water or air because of human activity

  • Point source

    • Comes from a specific place, such as a pipe or gas leak

  • Nonpoint source pollution

    • Comes from a broad area

    • Sediment and nutrients are common forms of nonpoint source pollution

• Sediment

  • Soil washed away by erosion

    • Plants can prevent excessive erosion

  • Sediment is harmful to water

    • Absorbs suns energy, causes water to heat up. warm water holds less oxygen than cool water

    • Makes it harder for creatures to see food

    • Clogs gills of sea creatures

    • Covers rocks that organisms lay their eggs on

• Nutrients

  • Most commonly nitrogen and phosphorus

  • They come from:

    • Fertilizers used by people are common forms of nutrient pollution

    • Animal waste produced by livestock also contains these nutrients

    • Human sewage

  • Harmful effects of too many nutrients

    • Algae blooms

    • Illness

    • Used up oxygen

Land Use

• Trees and plants protect from pollution

  • Roots prevent erosion

  • Leaves shade streams and keep them cool

  • Roots take in nutrients that would have entered the water

• Development removed much of this green space

  • Land became more susceptible to erosion

  • Livestock waste caused nutrient pollution

  • Increase in impermeable surfaces, causing more runoff

  • More pollution is washed into the watershed

Prevention of non-point source pollution

• Plant cover

• More permeable surfaces

• Proper disposal of waste

• Use fertilizer sparingly

• Stream buffers