"Today's water
crisis is the logical consequence of the "waste/water"
illusion. Where water is a waste vehicle and anything can be a
waste, no water resource is safe. Our culture is permeated with
this "waste/water" illusion. It is instilled in one
of the earliest and strongest lessons in childhood - toilet training.
It is reflected in the design and operation of every conventional
home, city, business, factory and farm."
Contamination of water
supplies
Most year-round rivers
are sites of urban, peri-urban and agricultural activities. Their
water catchments are subject to intense pressure from agricultural
and housing activities. Consequently, most of the larger rivers
experience a variety of pollution problems. Smaller rivers adjacent
to bush farming, mining and forestry activities are also subjected
to heavy sediment loading from erosion and chemical pollution.
Water contamination
is an old and serious problem in New
Zealand. Although many waterways still have water contamination
problems, there have been significant advancements made since
the last century. Typhoid and cholera are no longer the pervasive
threat that they were and a great deal of effort is now being
turned towards restoring water quality in streams and rivers.
Everybody, including
the plants and animals, needs safe drinking water. Living creatures
are molecular filters, removing protozoans, bacteria, viruses,
and even individual atomic elements from the water as it passes
through us. Our bodies are able to get rid of most undesirable
elements through an elaborate system of defence mechanisms. But
some of the contaminants defeat our biological capabilities and
accumulate in our bodies.
Many of New Zealand's
rivers, creeks and lakes are contaminated by the deliberate or
accidental discharge of sediment, chemicals or sewage. Various
kinds of pollutants do different things to the people and creatures
that depend on or live in the rivers and lakes.
The amount of damage
depends on the concentration and duration of the pollutant. In
some instances, very high concentrations of a poison might pass
through a river in a short time, but kill off a wide variety of
important species. Contamination of this sort is often from industry
and urban discharges. Because the discharges enter the water from
pipes, they are called "point source pollution." Rapid,
highly toxic discharges might include cleaning milk vats with
lime or metal plating vats with acids. The residues being cleaned
and the cleaning solvents are often highly toxic. Of course this
is illegal, but if it is done quickly and at night it is often
difficult to find out who did it. Today, new monitoring and testing
techniques can "fingerprint" chemical solutions and
trace a pollutant back to its source.
In other cases, small
amounts of pollution entering a river over a long time can cause
extensive damage to the balance of life or reproductive abilities
of the creatures. For example, agricultural run-off and fall out
from atmospheric pollution is diffuse and is called "non-point
source pollution." The effects of chronic and diffuse pollution
are difficult to assess and as many people are often involved,
correcting the problem is not easy.
Some of the more important
pollutants in New Zealand and their impact on rivers are:
A survey of the New
Zealand Regional council officials, responsible for water quality,
resulted in a prioritised list of sources of water quality pollution.
Agriculture was the most significant source of pollution. The
local severity of the problem depended on the particular river,
lake, or ground water system examined, and who examined it.
Sources of Impacts
on Water Quality, ranked by New Zealand regional council officials.
From Statistics New Zealand 1993. 0 = No damage and 10 = Severe
damage:
AVERAGE / SOURCE
OF IMPACT 4.9 Primary
agriculture
4.8 Human sewage
3.9 Urban storm
run off
3.8 Industry
3.7 Agricultural
processing
2.6 Mining
2.6 Forestry
0.7 Other
Pollutants of fresh
water that are especially hazardous to both human and natural
life systems include heavy metals, such as lead, mercury, chromium,
plutonium and arsenic. These are very difficult for living systems
to deal with and the build up in tissues and pass from one organism
to another. Once ingested, they remain in the body until death
(or unless special chealating agents are used to remove them).
If people eat creatures - such as fish or molluscs - containing
heavy metals, the metals become even more concentrated in them.
Highly Toxic Wastes
that contaminate fresh water (Statistics New Zealand 1993) include:
Heavy metals make humans,
stock and wildlife extremely sick. At low doses, they impair the
nervous system causing depression and fatigue. As they accumulate,
this becomes worse and co-ordination begins to fail. In times
of stress or starvation, the heavy metals are released back into
the blood as fat is burned. The high levels then disrupt all normal
body functions and the liver and kidneys fail causing death.
Pesticides containing
chlorine are also very difficult to
get rid of. Once ingested, they pass into fat and bone tissues.
Some of the fat tissue surrounds nerves and reproductive organs.
As the poisons accumulate, they begin to interfere with normal
metabolic processes. The rate of damage depends on how contaminated
the water is and the age of the person drinking it. Young (of
people and wildlife) are more easily poisoned by these chemicals
than adults. The health problems that result can lower spirits
and productivity. Over time, the poisons can become so concentrated
they destroy the ability to have normal children. In sufficient
doses, the contaminants may cause cancers or death by poisoning.
As with heavy metals, stress or starvation will release the poisons
from fat tissues and cause acute poisoning symptoms.
Extensive sampling
of rivers and streams on the Southland Central Plain of New Zealand
revealed serious deterioration of key indicator species in the
streams and a possible correlation with the absence of these organisms
and pesticide use. Nitrate levels in agricultural wells exceeded
the WHO guidelines of 10gms/m3 for drinking waters. Pesticides
were found in 11% of wells in agricultural areas. Chemicals associated
with timber treatment practices forced the recent closure of a
children's camp in the small South Island town of Hanmer Springs.
Routine water testing near the town found that timber treatment
chemicals had leached into the water course. (Statistics New Zealand
1993).
Eight percent of public
water supplies in New Zealand fail to meet microbiological standards.
Twenty six percent of chlorinated supplies failed to meet standards
for disinfection by-products. Three quarters of water supplies
that used aluminum in the water treatment process exceed the WHO
guidelines for aluminum.
