Agricultural runoff occurs when rain or snowmelt runs off the land to deposit sediment, nutrients, pathogens, pesticides, and salts directly into the river. Agricultural activities that pollute the river may include confined animal facilities, grazing, plowing, pesticide spraying, irrigation, fertilizing, planting, and harvesting. Agricultural runoff is a source of water quality deterioration and also a major contributor to ground water contamination and wetlands degradation. Agricultural activities also can damage habitat and stream channels.
Nutrients may cause excessive algal growths that absorb additional sunlight and release offensive odours and toxicants. If contacted or ingested in sufficient quantity, pesticides pose a health hazard to all forms of life. Water supplies can also be jeopardized by the presence of pesticides or algal growths and purification expenses can be expensive.
Added sediments may remain suspended in the water column and block sunlight needed for oxygen-producing plants. This sediment-laden water will also absorb more heat from the sunlight making the water warmer, which could displace many temperature dependant species such as fish. Additionally, sediments can choke waterways, reducing their capacity to carry water, prevent flood control, and reduce water quality. Sediments can also silt up fish spawning habitat.
For more information, check the River Report.
There are farmers making sustainable choices and leading the way in environmental conservation. An example is Dobson Farm. There is a large difference between an organic family farm and a large-scale industrial farm and the latter is certainly a much more significant contributor to environmental degradation and decreased water quality. Dobson farms has worked to reduce runoff and create wildlife habitat through the use of buffer strips along the nearby streams. They have also implemented an alternate watering system for the livestock.