Pollution
There are two main types of pollution,
point source pollution and
nonpoint source pollution. Point source pollution comes from one source (you can easily point to it) like a
factory or waste water treatment plant. Nonpoint source pollution comes from many
diffuse sources.
There is a common misconception that most of the pollution in our water comes from
industrial pipes dumping toxic wastes into water, but this point source pollution
has largely been controlled by the Clean Water Act and other legislation. A large
amount of pollution found in our waterways actually comes from nonpoint source pollution.
Point Source Pollution
Definition
Section 502(14) of the Clean Water Act defines point source pollution as, "...any
discernible, confined and discrete conveyance, including but not limited to any pipe,
ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock,
concentrated animal feeding operation, or vessel or other floating craft, from which pollutants
are or may be discharged.This term does not include agricultural storm water discharges
and return flows from irrigated agriculture."
Examples:
• Industrial plants/factories (e.g., oil refineries, pulp and paper mills, chemical
manufacturers, automobile manufacturers, food processors, pharmaceutical manufacturers)
Pollutants: oil, thermal pollution, toxic chemicals, heavy metals
• Sewage Treatment Plants
Effects

Excess nutrients (such as nitrogen and phosphorus) from sewage treatment plants can
overstimulate growth of aquatic plants like algae. Although plants give off oxygen
when they are alive, during decomposition
dissolved oxygen is consumed. This can harm aquatic life like fish and insects that need dissolved
oxygen to survive.
Pollution from industries occurs when water is used in production processes and then
is discharged into waterways without proper treatment. Pollution from industrial entities
are industry specific. For example, some power plants use water to cool overheating
equipment. If this water is not cooled before being released back into natural waterways
it can alter the temperature of that waterway. Certain fish and other aquatic animals
can only survive in cool temperatures so the warmer water that is released can alter
ecosystems.
Control Mechanisms
Allocations to point source pollution are implemented through permits that are consistent
with Total Maximum Daily Load (TMDL) reports. A TMDL is a calculation of the maximum
amount of a pollutant that a water body can receive and still meet water quality standards.
It also includes an allocation of that amount to the pollutant's sources.
The permits are issued by the EPA or states and tribes.
Nonpoint Source Pollution
Definition:
The term "nonpoint source" is defined to mean any source of water pollution that does
not meet the legal definition of "point source" in the Clean Water Act (defined above).
An example of nonpoint source pollution would be rainfall or snowmelt picking up natural
or anthropogenic pollutants and depositing them into water resources. In towns and
cities where much of the land is covered by impervious surfaces (such as parking lots,
sidewalks, rooftops, and driveways) water will flow into storm drains that carry the
water directly to your local streams or lakes. This is referred to as urban stormwater.
Examples:

• Urban runnoff
Pollutants: oil, grease, toxic chemicals,
nutrients
• Poorly managed construction sites
Pollutants: sediment

• Irrigation practices
Pollutants: salt
• Abandoned mines
Pollutants: acid drainage
• Livestock operations, pet wastes, faulty septic systems
Effects

Nonpoint source pollution is the leading cause of water quality problems according
to many states. Excess nutrients (such as nitrogen and phosphorus) from agricultural
land uses like fertilizing, concentrated animal feeding operations, and pesticide
spraying may run off into streams and rivers. This increase in nutrients may overstimulate
growth of aquatic plants like algae. Although plants give off oxygen when they are
alive, during decomposition
dissolved oxygen is consumed. This can harm aquatic life like fish and insects that need dissolved
oxygen to survive.
Construction or logging efforts can cause a significant increase of sediment in nearby
waterways. The removal of vegetation exposes soil and without vegetation to take-up
water there is a greater erosion potential. Suspended solids (turbidity) from erosion prevents sunlight from reaching aquatic plants. Without light photosynthesis
cannot take place, which may reduce the amount of dissolved oxygen in the water. Dissolved oxygen is vital for fish and other aquatic life. Sediment
absorbs heat, so if there are a lot of suspended sediments the temperature of the surface water can rise. Turbidity can also make it hard for fish to see their
prey. Heavy loads of suspended solids can even clog fish gills and filter-feeding
devices of aquatic macroinvertebrates (water bugs). As solid matter settles, it may
cover and harm plants and animals and spawning beds.

Drainage or runoff from abandoned mines may also contribute to nonpoint source pollution.
If air, water and sulfur-containing rocks mix, chemical reactions can lead to the
formation of sulfuric acid and iron hydroxide. This acid runoff dissolves certain
heavy metals (e.g., copper, lead and mercury) which contaminate waterways. Acid mine
drainage can also affect the
pH of water. Water with an extremely high or low pH is deadly. Water with relatively
low pH (acidic) may reduce the hatching success of fish eggs and irritate fish and
aquatic insect gills and damage membranes.
Control Mechanisms

There is currently no federal enforcement for nonpoint source pollution. Nonpoint
source pollution is primarily controlled by state, tribal, or local agencies that
develop management programs. Many of these programs use
Best Management Practices (BMPs), which are technical on-the-ground controls that can reduce nonpoint source pollution.
An example of a BMP would be creating a vegetation buffer between an animal feeding
operation and a stream. The vegetation can help take-up and filter nonpoint source
pollutants like nutrients and sediments.