Water Pollution


In this lesson you will learn about possible sources of pollution to water, both surface and underground water. Then you will follow the progress of water in a stream to determine the ultimate resting-place for the pollution.


Find a small stream near your school on a topographic map. Pollution has been detected at the mouth of this stream. Your job is to try to find all possible sources of pollution in the stream's drainage basin, and then also to see where the pollution will go if it isn't removed from the stream. Remember, pollution can get into a stream by moving downward through the soil to the water table, then traveling underground until it reaches a stream. For the purposes of this exercise, assume that all groundwater in the basin flows into the basin's streams, not into another drainage basin. Groundwater doesn't always stay within one drainage basin the way surface water does.

1. Start by outlining the drainage basin of your stream on the topographic map.

2. Using the list below, and any other pollution sources you can find, mark the location of each possible source of pollution on you map with a number. In the table, list the type of pollution source, the kind of pollution which might be released there, and what damage the pollutant may produce. This will involve consulting with others about the various types of businesses in the basin, traveling around the basin to look for pollution sources, and checking with your city or town government to find out where there is public water and sewer service. A good source for major pollution sources is the Leachate and Wastewater Map put out by DEP. Your town offices probably have the one that covers your area. There are 9 for the state. Or they are all available on a CD. Each shows major, known pollution points with an explanation about each site.

3. Explain where the pollution you discussed will travel when it reaches the mouth of your local stream. Continue following the most likely path of the pollution and explain where you think the pollution will finally end up. You may need to use other maps to find the ultimate resting-place of the pollution.

4. What is the ultimate deposition site of polluted water in your stream? You may need to go to other maps, as your stream may leave the area covered by your topo sheet.

5. Write a short essay on what could be done to prevent the possible sources of pollution you have identified from entering the stream.

Site number

Location of possible pollution

Type of pollution

Damage pollution may cause






























Types and Sources of Pollution

Fuel storage and transport 

  • Underground 
  • Above ground 
  • Spills during transport

Road salt

Industrial chemicals 

  • Accidental spills 
  • Leaking underground tanks 
  • Outdoor storage areas 
  • Improper handling of chemicals or wastewater 
  • Pipeline leaks (pipelines are shown of topo maps)

Agriculture and lawns 

  • Pesticides, manures and fertilizers 
  • Animal feed lots (manure)

Septic systems and sewage treatment plants

Landfills, industrial wastewater lagoons, sludge piles

Commercial facilities 

  • Automobile services 
  • Machine shops 
  • Dry cleaners 
  • Furniture strippers 
  • Printers 
  • Photoprocessors 
  • Medical and veterinary offices 
  • Laboratories 
  • Funeral homes

High-density residential areas, especially with no sewer service 

  • Older areas where septic systems were installed before current health standards 
  • If septic systems not properly maintained 
  • If hazardous chemicals poured down drains 
  • If chemicals or petroleum products poured on ground 
  • More impervious surfaces, so more runoff

Transportation corridors 

  • Impervious surfaces, especially parking lots, which accumulate oil leaks from vehicles 
  • Hydrocarbons 
  • Heavy metals 
  • Salt 
  • Potential spills 
  • Little vegetation for filtering


  • Hospitals and school labs involve hazardous chemical usage 
  • Nursing homes and prisons produce lots of domestic sewage


  • Sediment and runoff


  • Construction 
  • Timbering 
  • Agriculture

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