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Farm Runoff: A Threat to Freshwater Sources and You

Water quality and agricultural practices in the United States are fundamentally bonded. In most cases, our health directly corresponds to the quality of food and water we consume. Farming practices, particularly the process of fertilization, send nitrogen and other nutrients into the freshwater supply. The resulting decline in water quality affects all who use that water source. But what are nutrients, and why is runoff from farming such a problem?

Runoff pollution from farms affect local waterways and ecosystems. ©FiledIMAGE/envato
Runoff pollution from farms affect local waterways and ecosystems. ©FiledIMAGE/envato

Every living thing requires nutrients. Nutrients such as minerals, vitamins, proteins, carbohydrates, fats, and water are compounds in foods essential to life and health. Nutrients provide energy, promote growth, and maintain the chemical reactions necessary to maintain life.

Soil, a major source of nutrients, obtains them naturally from decaying organic material, rain, and eroded rocks and minerals. Vigorous soil has all the essential nutrients in the right proportions to support plant growth. Most soils, however, need additives to produce healthy crops and pastures. And all those additives affect water quality.

Soil also holds metals and pathogens which together with the nutrients often end up in agricultural runoff. The runoff flows into surface waters–lakes, rivers, and oceans–and leaches downward to groundwater. Here’s how it typically happens: a farmer fertilizes a field or pasture and is rewarded with abundant crops. However, the fertilizers, pesticides, and other soil enhancements wind up as polluted agricultural runoff.

Waterways Gather Pollution from Every Source

Algal bloom on lake. ©mstandret/envato
Algal bloom on lake. ©mstandret/envato

Nutrient overloads can cause great harm to the environment by polluting freshwater sources. The nutrients and bacteria-laden runoff can cause water to become smelly and slimy, prompting officials to close waterbodies to swimming and fishing. And while some algae are necessary to aquatic life, an overload, called an algal bloom, kills much of that life. Excess algae consume the water’s oxygen resulting in dead zones in which aquatic plants and animals cannot survive.

Two types of pollution impact water quality: point source pollution and nonpoint source pollution (NPS). Point source pollution comes from only one discrete source, a manufacturer’s smokestack, for example. Historically, drainage pipes from farms and industry dumped excess water directly into water bodies. The Clean Water Act stopped much of that. Now, facilities that want to pipe discharge directly into surface waters must first obtain a permit from the U.S. Environmental Protection Agency (EPA).

Nonpoint source pollution occurs from contaminating activities coming from multiple starting places. One example would be water deposited from rain that picks up various contaminants as it flows across the land. It picks up everything from fertilizers, herbicides, and insecticides to the excess salt from irrigation. Livestock waste contributes bacteria and more nutrients to the flowing water. Soil erosion adds sediment. All those substances, organic and inorganic alike, significantly impact water quality.

Solutions Start with Smart Farming Techniques

Much can be done to solve the problem of agricultural runoff. Farmers can manage the fertilizers they use by following the 4 “R”s of nutrient management:

  • The right source – spreading the fertilizer that best meets the soil’s needs

  • The right rate – applying only the amount the crops require

  • The right time – adding fertilizers when the crops most need them

  • The right place – spreading the fertilizer on the crops without touching adjacent fields or waterways

Farmers can also engage in best management practices (BMPs). Some BMPs can be conducted relatively easily and often cost less than indiscriminate use.

Conservation drainage techniques can be employed, such as adapting drainage design or digging trenches to hold woodchips and other carbon sources for water drainage. Or farm workers can create a buffer zone between a crop and its adjacent land or waterway by planting groundcover, shrubs, and trees.

With ordinary tilling, the land is broken to a depth up to several inches. Alternatively, infrequent tilling can be employed, which reduces erosion. In no-till farming, a farmer creates rows just deep enough for seed placement. By not plowing, plant remnants are left on the soil surface that minimize soil erosion, and also improve the nutrient content of the soil.

Pesticide use can be decreased by using predatory insects like ladybugs and spiders to control crop-destroyers such as Japanese beetles.

Finally, keeping livestock out of water bodies helps prevent bank erosion and contamination with manure.

Plant Genetics, Careful Irrigation, and Buffer Zones Reduce Harm to Water

Technologies developed in the past decade to combat NPS pollution include seed genetics, which combines cultivated plants with wild ones to produce plants resistant to drought and disease.

Precision agriculture enables farmers to use their tractors’ GPS, sensors, and satellites to monitor the health of their crops and precisely place fertilizer where and when it is needed. This method saves money and cuts down on NPS pollution. Another tool considers soil, topography, and farming methods being used. Information garnered aids the farmer in buffer zone placement and in deciding when and where to use fertilizer.

An additional solution includes installing a retention pond to catch runoff and filter pollutants. Restored or created wetlands can collect sediments and pollution.

Governments Monitor and Safeguard Water Health

State governments, tribal entities, academic institutions, and volunteers monitor water quality through the EPA’s National Nonpoint Source Monitoring Program. When officials consider the status of freshwater quality, several factors determine its health. Water is sampled for pollutants such as pesticides, metals, and oil, and naturally occurring substances like nutrients, bacteria, and dissolved oxygen.

The Chesapeake Bay in Maryland, USA ©Steve Adams
The Chesapeake Bay in Maryland, USA. ©Steve Adams

Some states promote good nutrient and runoff management, although they all have blind spots according to project scientist and aquatic ecologist Doug Strom. One notable example is the Chesapeake Bay watershed, which covers the District of Columbia and portions of six other US states. Increasing populations, such as those of the Chesapeake region, need to grow more food, possibly leading to excessive nitrogen and phosphorus levels throughout the watershed. Increased industry and agriculture may necessitate forest clearing and wetlands destruction.

On the bright side, Strom referred to a new project being conducted by scientists at Florida’s Saint John’s River Water Management District. A harvesting device will collect algae from a lake. New technology will be employed to separate the algae from the water. Workers will then return the clarified water to the lake and the algae will be treated at a wastewater treatment plant.

The Right Resources Empower Everyone to Take Action

American farmers, ranchers, and foresters can find financial and technical help from the USDA’s National Resources Conservation Service (NRCS). The website also has information about programs listed by state.

Agricultural operations take a huge toll on water quality. Through the use of best management practices, new technologies, and government-run programs, there is much that can be done. But with many bodies of water badly polluted, significant work remains.

Even so, individuals, communities, and policymakers can support water resiliency efforts. Americans can learn about local water issues, volunteer, or even contact elected officials. Visit the US EPA website, “How’s My Waterway?” to learn more about specific waters throughout the nation.

To be informed and proactive is to be one step closer to clean freshwater sources. And that will benefit us all.


*Cassie Journigan is a writer and editor who lives in the north-central region of Florida in the United States. She focuses on issues related to sustainability. She is passionate about numerous topics include the Earth’s changing climate, pollution, social justice, and cross-cultural communications.


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