Lesson 1:  Agricultural Practices that Affect our Watersheds

Several agricultural processes contribute to watershed pollution in Pennsylvania and beyond. The primary pollutants include nutrient runoff, sedimentation, pesticides, and livestock waste. Here’s how different farming activities impact water quality:

1. Nutrient Runoff (Nitrogen & Phosphorus Pollution)

• Cause: Over-application of fertilizers, manure spreading, and improper timing of applications (e.g., before heavy rain).

• Effect: Excess nutrients wash into streams and rivers, leading to eutrophication, which depletes oxygen levels in water bodies and causes harmful algal blooms (HABs).

2. Soil Erosion & Sedimentation

• Cause: Tilling, deforestation for farmland, and lack of cover crops expose soil to erosion.

• Effect: Sediment runoff clogs waterways, disrupts aquatic habitats, and increases water treatment costs.

3. Pesticide & Herbicide Contamination

• Cause: Spraying of chemical pesticides and herbicides on crops, which can run off during storms or leach into groundwater.

• Effect: These chemicals harm aquatic life, contaminate drinking water, and disrupt ecosystems.

4. Livestock Waste & Pathogens

• Cause: Manure from concentrated animal feeding operations (CAFOs) and pasture runoff introduce bacteria (E. coli, salmonella) and excessive nutrients into water sources.

• Effect: This can lead to waterborne diseases and unsafe drinking water.

5. Irrigation & Water Overuse

• Cause: Excessive withdrawal of water for irrigation, especially during droughts.

• Effect: Reduces stream flow, affecting aquatic ecosystems and leading to increased concentrations of pollutants.

6. Improper Waste Disposal & Farm Infrastructure

• Cause: Leakage from manure storage pits, failing septic systems on farms, and improper disposal of agricultural chemicals.

• Effect: Leads to contamination of groundwater and surface water sources.