Farm Runoff:  What is it Anyway?

When we talk about farm runoff, we are referring to a broad spectrum of agricultural contamination.

Point source pollution and diffuse (nonpoint) source pollution are the two broad categories that define where this stuff comes from.</p>

Point source pollution is contamination that can be traced back to a single point of origin.  

Examples would be undiluted animal manure, called slurry, or milk spillage, or something called silage liquor which is farm runoff from fermented wet grass and other fodder.  

Silage is a broad name for fodder that is converted to livestock feed through a fermentation process, usually in a silo.  

Diffuse source pollution is runoff that is harder to pinpoint since it can come from a wider area and from
multiple sources.  

Fertilizers, pesticides and herbicides that are widely spread on fields are diffuse sources.  They end up in drainage ditches, then streams, rivers and eventually end up in our lakes and oceans.

The problems these contaminants cause all get back to something called their high biological oxygen demand (BOD).

Photo:  Algae bloom in waterway from excess nutrient runoff resulting in oxygen depleted water

Oxygen depleted waterway and resultant algae bloom

They all have a high nitrate concentration which causes high levels of nutrient pollution in the waterways. 

The excess nutrients cause algae blooms that rob the oxygen from the water.  The process is called eutrophication.  Just thought I would throw that in, now forget it.

The end result is the death of water plants, then fish, frogs and other denizens of the waterways.

Decomposition from all those dead bodies increases bacteria, depleting oxygen levels even further. 

Soon we are left with a "dead" body of water, no life, nada.

Certain types of algae produce toxins that can kill wildlife.  In humans, contact can cause skin rashes and ingestion can result in pains and stomach upsets.

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Under certain conditions, nitrates in drinking water can prove fatal to babies.

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Somewhere along the line, farm runoff eventually makes it into our drinking water and we need to protect our families.
A highly recommended system for the kitchen is AQ-4000 Counter Top Water Filter from Aquasana. 

It reduces chlorine, chloramines, trihalomethanes, volatile organic compounds, pesticides, herbicides, and foreign tastes and odors below detectable levels for safer, healthier water.

Spectrum of Farm Runoff Contaminants

Photo:  Farmers dumping milk on field in price protest; this action caused incredible damage to the immediate environment.  Milk has the highest biological oxygen demand (see below)

Dumping milk on a field in price protest

Typical farm runoff (agricultural pollutants) has enormous biological oxygen demands as shown in the bullets below. 

No one wants to shut down the farms (we still have to eat), but good agricultural resource management seems to point to a greater awareness and control of the hazards to our drinking water and natural waterways from farm runoff.

  • Milk spillage or dumping: 140,000 ppm
  • Silage liquor: up to 80,000 ppm
  • Pig slurry: up to 30,000 ppm
  • Cattle slurry: up to 20,000 ppm
  • Liquid sewage sludge: 20,000 ppm
  • Domestic sewage: 300-400 ppm
  • Treated sewage: 20-60 ppm
  • Vegetable washings 500-3000 ppm

Farm Runoff is Rampant but Manageable!

The most recent National Water Quality Inventory from the EPA reports that agricultural nonpoint source (NPS) pollution is the leading source of water quality impacts to surveyed rivers and lakes, the third largest source of impairments to surveyed estuaries, and also a major contributor to ground water contamination and wetlands degradation.

Agricultural activities that cause NPS pollution include confined animal facilities, grazing, plowing, pesticide spraying, irrigation, fertilizing, planting, and harvesting.

The major agricultural NPS pollutants that result from these activities are sediment, nutrients, pathogens, pesticides, and salts. Agricultural activities also can damage habitat and stream channels. 

The USDA and EPA have numerous programs in place to monitor and control these nonpoint sources of pollution as described in the following paragraphs.

The EPA has a very detailed webpage on polluted runoff from agriculture with numerous links to various webinars and other articles on the subject.

It can be viewed at polluted runoff-agriculture.

Farm Runoff:  Sedimentation

First they try to manage Sedimentation that occurs when wind or water carries soil particles from an area, such as a farm field, and transports them to a water body, such as a stream or lake.

Photo:  Sedimentation builds up on breakwaters because they slow the water flow and the stream can't carry as much sedimentation load.

Sedimentation buildup on breakwater

Excessive sedimentation clouds the water reducing the amount of sunlight reaching aquatic plants; covers fish spawning areas and food supplies; and clogs the gills of fish.

In addition, other pollutants like phosphorus, pathogens, and heavy metals are often attached to the soil particles and wind up in the water bodies with the sediment.

Erosion and sedimentation can be reduced from 20 to 90 percent by applying management measures to control the volume and flow rate of runoff water.

Farm Runoff:  Nutrients

Second, they attempt to manage nutrients. When Phosphorus, nitrogen, and potassium fertilizers, manure, sludge, irrigation water, legumes, and crop residues wash into aquatic ecosystems they can cause excessive plant growth (see algae bloom photo above).

This spoils recreation areas, creates a foul taste and odor in drinking water and kills fish. In drinking water, high concentrations of nitrate can cause methemoglobinemia, a potentially fatal disease in infants, also known as blue baby syndrome. 

Farm Runoff:  Confined Animals

Third, they try to manage confined animal feeding facilities. 

Of course, this is not a problem with fully grass fed pastured cattle or hogs such as supplied by Snake River Farms or Double R Ranch shown in the link above.  In addition, to avoid overgrazing shown in the paragraphs below, pastured animals from family farms are typically rotated among pastures thus allowing the grazed land to recover. 

Environmentally, this is a major benefit of the small independent farms as opposed to the CAFOs or corporate run industrial sized farms.

Bigtime waste producers Cow pens, major source of farm waste

These confined areas can become major sources of animal waste where runoff can carry pathogens (bacteria and viruses), nutrients, and oxygen-demanding substances to sensitive areas.

Ground water is also contaminated by seepage. Discharges can be limited by proper storage and management of wastewater and runoff.

Photo top:  Confined hogs and cows; the source of much farm waste and eventually, contaminated water

Hog waste to hog lagoon to water table

Photo:  Hog lagoon; holding pond for hog waste.  Through flooding and seepage, will find its way to the water table

Farm Runoff:  Irrigation

Fourth, they attempt to manage Irrigation and avoid inefficiencies that can cause serious water quality problems.

Photo right:  Irrigated (flooded) wheat field

Photo left:  Efficiently irrigated New Jersey field

Basin flooded wheat field Irrigation system on NJ field

In arid areas rainwater does not carry residues deep into the soil and excessive irrigation can concentrate pesticides, nutrients, disease-carrying microorganisms, and salts, all of which impact water quality in the top layer of soil.

Farmers can reduce NPS pollution by matching irrigation with actual crop needs.

Farm Runoff:  Pesticides and other "Cides"

Fifth, they manage pesticides, herbicides, and fungicides.  These chemicals can enter and contaminate water through direct application, runoff, wind transport, and atmospheric deposition.

They can kill fish and wildlife, poison food sources, and destroy the habitat that animals use for protective cover.

To reduce NPS contamination from pesticides, people can apply Integrated Pest Management (IPM) techniques which help limit pesticide use and manages necessary applications to minimize pesticide movement from the field.

Farm Runoff:  Grazing

Last is the Management of livestock grazing that exposes soils, increases erosion, encourages invasion by undesirable plants,

Severely trampled ground

destroys fish habitat, and reduces the filtration of sediment necessary for building stream banks, wet meadows, and floodplains.

Photo left:  Severely trampled ground from overgrazing

Photo right:  Former wetland ruined by overgrazing

Overgrazed wetland

To reduce the impacts of grazing on water quality, farmers and ranchers can adjust grazing intensity, keep livestock out of sensitive areas, provide alternative sources of water and shade, rotate cattle among grazing areas, and re-vegetate range land and pastureland.

You can see in work at Fossil Farms by clicking their link below; watch their amazing videos while you are there. 

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