Connecticut Water Trails Association
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Connecticut Water Trails Association |
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Connecticut Water Trails Program Rivers
River Pollution
Nearly everything that can be found on land eventually makes its way to a river. This is because every bit of ground on Earth is a part of some river's watershed. Water flows downhill. Whether the water comes from rain, a hose, or a pipe, whatever doesn't sink into the ground will flow into the nearest stream. That is a simplification, of course. In reality, much of the water that soaks down into aquifers also eventually finds its way to a stream.
The things that belong in a stream are the things that have been flowing into the stream for thousands or even millions of years. They are things that the plants and creatures in the stream have evolved to use to their advantage. They include very low concentrations of chemicals like calcium, iron, phosphorus, and nitrogen. They also include things you can see, like bugs, sediment, leaves, twigs, dead animals, even tree branches and whole trees.
The things that don't belong in a stream--things
that didn't show up there until human technology began to upset stream
ecosystems--are called pollutants. According to theories of
evolution, even a stream filled with a toxic soup of industrial
chemicals may one day be able to support life. The problem is that it
will take millions of years to get there.
Point-Source Pollution
Regulations developed since the 70's have greatly
helped to cut down on point-source pollution, which is pollution
that enters streams from industrial and agricultural sites. That doesn't
mean the pollution has gone away. Agricultural runoff from farms and
ranches still contains unsavory levels of bacteria, hormones,
pesticides, herbicides, excrement, and fertilizers, as well as large
amounts of sediment.
Many pollutants from earlier decades remain in
streambeds, building up in the bodies of fish and birds. These
pollutants include heavy metals, DDT, dioxin, polychlorinated biphenyls
(PCB's), and a number of recently banned pesticides. There are
underground storage areas of toxic chemicals as well that have begun to
leak into streams. A frightening example of this is the Hanford nuclear
storage site near Richland, Washington in the U. S.. A number of the
underground containers have begun to leak and radioactive materials have
found their way through cracks in the rock into the Columbia River.
Despite the fact that this disaster is so well known, modern countries
(including the U. S.) continue to generate nuclear waste and bury it
underground.
It must be remembered that rivers contain living
creatures and plants, many of them microscopic but very important
members of the food web that can be killed by pesticides and herbicides.
When part of the food web is eradicated by these chemicals, the animals
that depend on them starve or fail to reproduce. Fertilizers and animal
waste cause their own problems: they enrich rivers, causing the growth
of algae, removing oxygen from the water and blocking sunlight.
Sediments also block sunlight as well as cover riverbeds, choking and
killing off the plants and animals that live there. Hormones, which are
fed to livestock to increase production and excreted in their urine,
alter the reproductive processes of stream animals like fishes.
Urban Runoff
Fertilizers, pesticides, and herbicides don't all
come from farms, though. Most of them these days actually come from
peoples' lawns and gardens. This is part of urban runoff. Water
rushes over the many hard (impermeable) surfaces that humans
create, over roadways and into gutters, and from there through pipes to
the nearest stream. This type of pollution contributed by whole
settlements of humans is called non-point-source pollution. Urban
runoff also contains a toxic soup of cancer-causing chemicals
(carcinogenic hydrocarbons) that are deposited by cars, buses, and
trucks on roadways. Rainwater that runs off the road collects in
ditches, which run alongside the road collecting more toxins until they
finally empty into a stream. The toxins include chemicals like hexane
and cyclohexane, benzene, polycyclic aromatic hydrocarbons (PAH's),
formaldehyde, methanol, acrolein, 1,3-butadiene, and acetaldehyde, as
well as lead. If these chemicals can cause cancer, birth defects, and
immune suppression in humans, it is a good bet that they will do similar
damage to fishes and birds.
Sewage
Urban pollutants also enter rivers through
water-treatment plants. Water-treatment plants only clean out some of
the pollutants, leaving the rest in the treated water that they pipe
into streams. Most of the chemicals we put in our sinks, toilets,
washing machines, and bathtubs will end up in the local stream. The long
list of pollutants we contribute includes drugs like antibiotics,
antacids, digoxin, Viagra, and steroids; antidepressants like Prozac and
Wellbutrin; painkillers like caffeine, ibuprofen, acetaminophen, and
codeine; and the medicines we use to control cholesterol, diabetes,
asthma, coagulation, and hypertension. It includes reproductive hormones
like estradiol, progesterone, and testosterone. Indeed, most medicines
that we put in our mouths will later be found in the local stream, to
find their way eventually to bigger streams, and finally to estuaries
where young marine fish mature. The other chemicals we
use--antioxidants, anti-corrosives, solvents, the fragrances for our
laundry, and degreasers--will join them there.
Power Plants
Nuclear, natural gas, and coal power plants inject
heated water into rivers, raising temperatures above normal. This
heat pollution can cause a devastating change in river ecology.
Other pollutants are injected each time a plant cleans and flushes its
cooling system. Coal-fired power plants pollute the air with mercury,
which eventually falls on the land and runs off with rainwater, entering
streams and poisoning the animals in them--as well as the fishermen who
catch and eat their fish. Nuclear power plants must store their
radioactive and other toxic wastes, which eventually leak into water
tables and enter streams.
Mining
During the early years of gold mining, mercury was
used to separate gold from ore. This mercury remains in streambeds,
continuing to poison life long after the practice became illegal. Today,
the main pollutant from gold mining is sulfuric acid. Acidification not
only kills streams but also puts toxic metals found in the soils--such
as aluminum, copper, and cadmium--into solution, enabling them to enter
streams. Nearly all mining results in large quantities of acids leaching
into streams as well as runoff of heavy metals like lead, cadmium, and
arsenic. The government gives away lands to large mining companies,
often from foreign companies, for dirt-cheap prices. The mining
companies then extract their minerals and run off with the profits,
leaving the public to deal with often irreversibly polluted and toxic
lands. Runoff from piles of coal and coal mines carries cadmium, lead,
boron, chromium, mercury, arsenic, and selenium into streams. Runoff
from uranium mining operations transports heavy metals and radioactive
uranium into rivers. The fishes that we most like to catch are predators
near the top of the river food chain--salmon, trout, bass, sunfish, and
so forth--that have the highest concentrations of heavy metals in their
bodies. Mine leaching as well as coal-fired power plants and cement
plants that contribute mercury to our air have ensured that fish from
most of our streams--even many mountain streams--have become dangerous
to eat.
Sediment
Sediments also pollute rivers. Housing construction,
road construction, mines, and logging roads all contribute large amounts
of sediments to rivers. Sediment can make hunting food difficult for
stream residents, choke plant life, and coat gills of insect larvae and
fishes, making breathing difficult or impossible. Many of the diatoms
and tiny insects that form the base of the food web will die. This has
an effect all the way up the food chain. Finally, salmon and trout eggs,
deposited safely in gravelly streambeds, are choked by the extra
sediment and fail to mature.
What
Can Be Done?
There are many workable solutions for those who care
about the health of their streams. Citizens can monitor streams and keep
a watchful eye on industry, including farms, ranches, dairies, and
feedlots. Water-treatment plants can be upgraded to filter out more
pollutants. Urban runoff can be minimized by providing permeable areas
like gardens and rainwater collection pits. Vehicles with better
fuel-efficiency pollute less per mile. Good vehicle maintenance keeps
leaks and fumes in check. Lawns can be replaced with more
ecologically-friendly spaces. Home-owners can decline to use pesticides
and herbicides. New developments can be built using the latest in
environmental practices and the advice of biologists. Construction
companies can take steps to control sediment. Citizens can press for
more ecologically-friendly forms of power, support organic farmers by
buying their products, and help educate their communities about
watersheds.
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