What is non-point source pollution?

Non-point source (NPS) pollution unlike pollution from industrial sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snow melt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water. These pollutants include:

Excess fertilizers, herbicides, insecticides, and organic material from agricultural lands and residential areas, which causes excessive algae and weed growth;

Oil, grease, toxic chemicals, pesticides, and herbicides from urban runoff and energy production, which causes reduced aquatic diversity and is harmful to humans.;

Sediment and sand from improperly managed construction sites, crop and forest lands, and eroding stream banks.  [The sediment destroys fish and insect habitat. Sediment may also cause local flooding] Some soil particles are primarily detached by raindrops but can also be detached by the shear forces resulting from overland or channel flow. Large sediment particles are less cohesive and therefore are more readily detached from the soil surface then the fine particles;

Salt from irrigation practices and acid drainage from abandoned mines; Which is normally described as the total dissolved solid (TDS) concentration. It can have specific damaging effects on soil and plants. Salts can cause clay particles to disperse and lose their permeability. Soluble salts in saline and alkali soils consist of calcium, magnesium, sodium, potassium, carbonate, bicarbonate, sulfate and chloride, and are easily leached from the soil.

Bacteria and nutrients from livestock, pet wastes and faulty septic systems; In simple terms, a pollutant is a substance that once it gets into the environment, tends to elevate the "natural" background level of that substance. In many cases, there may not be any amount of the "manufactured" substance there in the first place.

Every single person plays a role in producing non-point source pollution. Running your car, fertilizing your garden or lawn, or building onto your driveway or house, and even construction can produce NPS pollution. It's the hardest pollution to control because you can't put your finger on where it is coming from. A house 30 miles away may put fertilizer on their lawn and the next day it rains, all water qualities around it may be affected by it and maybe even our sources of drinking water. Everyone must take part in preventing NPS pollution to maintain our water's quality. We can start by carpooling and walking instead of driving everywhere, use little, if any, fertilizers and pesticides, and dispose of wastes properly.

This affects the watershed because all the land around a watershed is raised. So when it rains, snow melts, or anything that can cause NPS pollution to happen it runs down the sides into the water. Which, as stated above, can include sediments, and things that can either kill off the living species or over populate. And when too many fertilizers or anything that induces plant growth, it causes a process called eutrophication.