Raw sewage includes the flushings from toilets, the
water that drains from sinks, bath tubs, showers, and other faucets
in a home. The total collection of water leaving a home after use is
called wastewater or raw sewage. Because of the large amount of water
we use to wash away waste, our sewage is about 1000 parts of water for
every 1 part of waste. Up through the 1970's, numerous locations in
the United States dumped their sewage into the local waterways without
treating it first. The Clean Water Act of 1972 aimed to clean up the
nation's waterways and develop a system of sewage treatement plants
that treated waste water before it was released back into the streams
and rivers.
The results of dumping raw sewage prior to the 1970's
included contamination of water with pathogens (disease causing bacteria,
viruses, and other organisms), the killing of aquatic life, and the
contamination of drinking water. Included in waste water are debris
such as trash that are flushed down toilets or washed down storm drains,
organic material, dissolved organic material, and other contaminents
such as pesticides, soaps, heavy metals, and other toxic compounds.
The gentleman who owns the sewage collection company
described in the "Sewage Dumping" scenario empties private
septic tanks that are not connected to city sewer lines. This waste
has to be removed from a septic tank and transported to a treatment
facility. By dumping sewage into the stream he may be releasing all
or some of the above mentioned contaminants into the waterway. The effects
may be a decrease in dissolved oxygen because of the increase in bacteria
that breakdown the waste and use up oxygen in the process. A decrease
in dissolved oxygen would effect aquatic species such as fish and macroinvertebrates.
The release of excess nitrogen and phosphorus from the dumped sewage
may cause eutrophication and might cause an increase in algal growth.