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NON-POINT SOURCE POLLUTION: �IT BEGINS AT HOME!�ALEX KOSMIDER, U OF A COOPERATIVE EXTENSION

LEARNING OBJECTIVES:

1. Define non-point source (NPS) pollution and differentiate it from point source pollution using real-world examples from urban and rural settings.

2. Explain changes in watershed ecology that influence NPS pollution (Water cycle, nutrient cycles, carbon cycles, river continuum concept).

3. Identify major types, sources and pathways of NPS pollution in surface water systems, including stormwater runoff, agricultural fields, and impervious surfaces.

4. Describe the impacts of NPS pollution on water quality and designated water uses(e.g., recreation, fisheries, drinking water).

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THE CLEAN WATER ACT (1972): OUR MAIN WATER QUALITY LAW

Objective:

“To restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”

Regulatory strategy:

Control Point Source Pollution, because it’s

Identifiable
From human-made conveyances
Can be permitted, monitored, and treated

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POINT SOURCE POLLUTION DEFINED

EPA definition from Section 502(14) of the Clean Water Act:

The term "point source" means 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 stormwater discharges and return flows from irrigated agriculture.

It’s not what the pollutant is, it’s HOW it gets to the water.

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NON-POINT SOURCE POLLUTION IS EVERYTHING ELSE!

Pollution from many diffuse (not concentrated or distinct) sources, moved by stormwater or snowmelt to water sources.
Not dumped in directly.

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POINT SOURCE AND NPS POLLUTION COMPARED

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POINT SOURCE:�MUNICIPAL WASTEWATER TREATMENT PLANT

This human-made, discrete conveyance discharges treated wastewater directly at a known location and time, and with pollutant limits.

Unlike some famous Point Source Pollution events (like the 2010 Deepwater Horizon Oil Spill), these are everyday, mundane processes that fall under Clean Water Act regulation.

NON-POINT SOURCE:

STORMWATER RUNOFF

URBAN EXAMPLES

This diffuse source of pollution comes from many upstream areas, enters waterways indirectly (via stormwater and snowmelt) and is not regulated by the Clean Water Act.

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POINT SOURCE:�CONCENTRATED ANIMAL FEED OPERATION LAGOON (CAFO) OVERFLOW PIPE

This human-made, discrete conveyance discharges treated wastewater at a known location and time, and with pollutant limits.

NON-POINT SOURCE:

FERTILIZER RUNOFF FROM FIELDS

RURAL EXAMPLES

This diffuse source of pollution comes from many upstream areas and is not regulated by the Clean Water Act.

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A WATERSHED: THE LAND THAT “SHEDS” THE WATER TO A LOW POINT

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WATERSHED HEALTH DETERMINES WATERWAY HEALTH

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WHEN WE PROTECT THE WATERSHED (LAND) ECOLOGY (PLANTS, ORGANISMS AND SOILS), LESS NPS POLLUTION OCCURS

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WATERSHED ECOLOGY INFLUENCES ON NPS POLLUTION

Water Cycle
Nutrient Cycles
Carbon Cycles
River Continuum Concept

These cycles determine the initial impact of NPS, and then NPS can turn disrupt or change those cycles.

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1. THE WATER CYCLE: URBAN STORMWATER AND IMPERVIOUS SURFACES

Healthy watershed:

Rain mostly either soaks in (infiltrates) or evaporates.
Small amount of runoff
Vegetation slows down and decreases amount of runoff.

Unhealthy wateshed

Urbanization = more impermeable surfaces (parking lots, streets, rooftops) = less infiltration, more runoff.
Result: faster, dirtier water.

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2. NUTRIENT CYCLES (NITROGEN AND PHOSPHORUS)

Healthy watershed:

Healthy soils retain nutrients
Vegetation uses excess nitrogen and phosphorus.

Unhealthy watershed:

Less vegetation leads to unhealthy soils and more erosion
More nitrogen and phosporous enter waterways

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3. CARBON CYCLE

Healthy watershed:

Roots of vegetation retain organic material in soils
Less organic matter for microbes
More oxygen available for fish and fewer “dead zones”

Unhealthy watershed:

No vegetation to stop soil from eroding
More carbon in waterways from eroded soil
Increased microbial activity

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4. RIVER CONTINUUM �CONCEPT AND NPS:

Normal River Continuum:

Organisms break down large organic matter slowly as the river gets larger

Headwater leaf litter supports shredders (stonefly and caddisfly larvae) who break down leaves.
Mid-order streams make algae, which supports grazers and collectors like mayflies and snails.
Large rivers host collectors (midge and blackfly larvae) and predators (dragonfly larvae)

What happens upstream accumulates and transforms the downstream area

NPS-Polluted:

Excessive energy
Organic matter is finer (more Fine Particular Organic Matter or FPOM)
Nutrients more available
Flow is faster.
Organisms and their energy sources are out of balance, oversimplifying the food web and making it less resilient.
Clearer sign of NPS: larger number of collectors.

Finally, the River Continuum Concept describes how rivers are organized around how energy moves through them. In healthy headwater streams, shredders like stonefly and caddisfly larvae break down leaves from riparian vegetation. As water moves downstream, grazers like mayflies and snails feed on algae growing on rocks. Fine organic particles are then used by collectors like midge and blackfly larvae, and predators such as dragonfly larvae sit at the top of the food web.

Non-point source pollution disrupts this balance. Runoff increases sediment and fine organic matter while reducing leaf inputs and water clarity. This favors collectors and microbes but reduces shredders, grazers, and predators. Over time, the food web becomes simpler and less resilient. While the photo still shows a normal, healthy waterway, essentially with NPS, the diversity of insects, microbes, and other wildlife shifts to what you see in the last picture, throughout the river. The NPS Fine Particular Organic Matter flowing into upstream reaches means that there are fewer ecological niches to fill with shredders and grazers, so collectors dominate.

Now that we have talked about the watershed ecology that influences how much NPS makes it to actual waterways, let’s discuss some specific pollutants and the impact of agricultural runoff on downstream waterways.

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POLLUTANTS

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AGRICULTURAL RUNOFF: TOO MANY NUTRIENTS! CARBON, NITROGEN AND PHOSPHORUS CYCLES

Fertilizers and manure add nutrients to natural systems
Natural systems recycle nutrients slowly
Runoff causes eutrophication (excessively enriching a water body with nutrients).
Like adding fuel to a fire: the fire uses up all the oxygen in the room!

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IMPACTS ON WATER QUALITY FOR RECREATION

Human health impacts:

Exposure to chemical contaminants or pathogens from swallowing contaminated water
Skin contact
Eating recreationally-caught fish.
Murky water from major stormwater influxes
Cyanobacteria, which degrade into microcystins (allergic reactions, skin rashes, GI distress)

Ecological impacts

Visible dead fish
Algal blooms
Unhealthy plants.

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IMPACTS ON WATER QUALITY FOR FISHERIES AND AQUATIC LIFE

Mercury bioaccumulates in predatory fish, sometimes resulting in fish consumption advisories.
Sedimentation smothers habitat for some species.
Low dissolved oxygen makes fish lethargic and congregate near inflows or bubblers with higher oxygen concentration.
Fish sometimes needed to be brought in from external fisheries to eat weeds and algae.
Some kinds of algae (i.e., Golden Algae) are deadly to fish.

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IMPACTS ON WATER QUALITY FOR DRINKING

Increased treatment costs,

More filtration, chemicals, and energy needed.

Nitrate contamination

(Reduces blood’s ability to carry oxygen, especially in infants)

Taste and odor issues reduce public trust

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QUESTIONS?