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Pollution isn’t
what it used to be. Most people’s image of water pollution is a pipe
discharging industrial waste or sewage into a waterway. This “point
source” pollution – that is, pollution from a single, clearly
identifiable source – was once America’s major source of water
contamination. In the last 25 years most point source pollution has
been eliminated as industries and wastewater treatment facilities
cleaned up their discharge to comply with the Clean Water Act.
Although point source pollution has been reduced to a fraction of
its former levels, we still have significant amounts of water
pollution.
Today most water pollution comes from pastures, construction sites,
parking lots, housetops, lawns, and driveways. Nonpoint source
pollution is the contamination that rain washes off surfaces and
carries into streams and lakes. Because most pollution is now
“nonpoint source,” it’s often hard to find. A pipe pouring chemicals
into a river is easy to spot. But runoff comes from virtually
everywhere and carries a mix of pollutants with it.
Only 10% of the nation’s waters are polluted by “point
sources,” such as discharge from industrial plants and
wastewater treatment facilities. |
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Most waters are polluted by “nonpoint sources,” the
contaminants that rain washes off land, pavement and
roofs and are carried into streams. |
Although
there are specific, identifiable causes of nonpoint source
pollution, the most effective way to deal with the problem is on
a watershed basis. A watershed is simply all of the area that
drains into a particular body of water. A watershed may
encompass several communities, or even several states. And one
community may have several watersheds within its boundaries.
It’s important to deal with nonpoint source pollution on a
watershed basis because the permitting regulations with which
communities must comply are based on pollution totals within a
specific body of water.
A relatively small number of issues account for most of the
problems in the Kentucky River Basin. These problems were documented in the
Kentucky Division of Water’s most recent Report to Congress
as required by the Clean Water Act. Water quality issues in the basin
include straight pipes, contamination by animal waste, erosion
and siltation, alteration of flow, removal of streamside
vegetation, and contaminated stormwater, as well as some point
sources of pollution.
Straight pipes and failing septic systems.
Spillage of human waste into streams spreads disease and
makes waterways unsafe for recreation. It also causes
undesirable changes in stream ecosystems by reducing oxygen and
increasing phosphorus. This is a widespread and serious problem
throughout the state, compounded by geology that is poorly
suited to septic systems and by areas of steep terrain. Some
existing septic systems do not work properly and therefore are
almost the same as straight pipes. New technology for onsite
sewage disposal can help. Extension of sewer lines may also be
feasible in some areas.
Livestock and poultry manure contamination.
Animal waste that washes into streams can cause undesirable
changes in stream and lake ecosystems by reducing oxygen and
increasing phosphorus. It can also spread disease and make
waterways unsafe for recreation. Management practices can reduce
these loadings.
Siltation and turbidity caused by erosion.
Any exposure of soil that allows it to be washed away causes
problems at both ends: soil loss at the source and pollution of
the streams that the soil goes into. Particles of soil suspended
in the water (causing turbidity) disrupt stream life. Particles
that settle out (siltation) clog the streambed and change the
flow, causing more problems. Siltation is also harmful to stream
life. Sources of erosion include agriculture (both grazing and
row-cropping), logging, mining, construction, destruction of
vegetation (such as logging roads, off-road vehicle trails), and
modification or destabilization of stream banks. Best management
practices (BMPs) are techniques to minimize harmful side effects
from such activities.
Contamination of storm water.
Rain runoff from roads and towns carries pollution into streams.
Waste such as motor oil that is dumped on pavement or into storm
drains also contaminates the streams that the streets or storm
drains empty into.
Under the provisions of the Clean Water Act, states must assess
the quality of their waterways. When waterways don’t meet
standards, total maximum daily loads, or TMDLs, of various
categories of pollutants are established. The total maximum
daily load is the amount of each pollutant – from both point
sources and nonpoint sources – which a body of water can absorb
and still meet the water quality standards for its designated
use. Permitting of development or new industry is restricted if
it would result in the watershed exceeding its TMDL of a
specific pollutant.
There are six main types of nonpoint source pollutants. All six
can come from a wide range of sources.
Pathogens are harmful organisms in human and animal
waste. They can cause disease directly if you go into
pathogen-polluted water, or indirectly, if you eat shellfish
from contaminated water. Sources of pathogens include runoff
from pastures, failed septic systems and pet waste.
Nutrients include nitrogen and phosphorus from
fertilizers or animal wastes. They can cause a health hazard in
drinking water and stimulate plant growth in water. Oxygen is
taken up by plant growth and in the decay of organic material.
This lowers the level of dissolved oxygen in water and results
in fish kills.
Sediment is eroded soil from construction sites,
un-mulched planting beds, and bare fields. As much as six tons
of soil can wash off a single acre in a year if the soil is not
covered by vegetation. This soil settles out in streams and
lakes and smothers aquatic organisms and habitat, clouds the
water, and eventually silts up stream channels and even entire
waterways.
Thermal Stress refers to headed water that is the
results of rain or other water running across hot roofs, parking
lots, roads, and driveways. This heated water warms holds
less oxygen and can result in the death of many plant and fish
species. Also, when vegetation is removed along stream banks,
the lack of shade can significantly raise the temperature of the
stream, leading to fish kills.
Debris
is trash of any sort that washes off parking lots,
driveways, construction sites, and city streets and is carried
into waterways.
Chemicals include pesticides washed off lawns or farm
fields; oil, antifreeze, car fluids washed off roads…poured into
storm drains.
1. Pathogens 2. Nutrients 3. Sediment
4. Thermal stress 5. Debris 6. Chemicals |
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