Unit 5: Agriculture and Freshwater Pollution

In this unit, you will explore how agricultural practices can affect the water quality in streams, rivers, lakes and coastal areas. Important concepts in this unit include processes that transport suspended material (e.g., sediment) and dissolved material (e.g., nutrients) away from crop fields and into regional water bodies. The effects of dissolved nutrients on the health of the water ecosystems will be presented with examples of hypoxic zones in coastal areas and lake eutrophication.

Before Class

Before class, you will need to understand the concepts of non-point source (NPS) pollution and the process of nutrients and sediments moving from agricultural operations into water bodies. Ask your instructor which of the following resources that are publicly available:

• A good introduction is the EPA Non-Point Source Pollution website.
• A more technical and complete description of non-point source pollution from agriculture is found in Chapter 2 of the US-EPA (2003) USEPA (2003) Chapter 2 (Acrobat (PDF) 233kB Mar12 14)

In Class

Unit 5.1 Agriculture as a Source of Water Pollution

Your instructor will first give you some background on Non-Point Source (NPS) pollution and check that you have the concepts from the reading. You will then work in groups of four or five students to create a list of agricultural activities that can lead to the introduction of suspended and dissolved material into groundwater and surface water. Each specific activity should have a description. When time is up, have the groups share their findings with the rest of the class.

Remaining in your groups, you will discuss what are the components of NPS that are of concern. Each group will come up with a list of these components and differentiate between suspended and dissolved. Each component should have a definition and an example. Your instructor will then lead a wrap-up discussion.

Unit 5.2 Thinking in Systems: Modeling the Impact of Agriculture on the Eutrophication Process and the Development of Dead Zones

Eutrophication of coastal areas linked to excess nutrient input from rivers that drain agricultural regions has led to hypoxic regions or "dead zones." Your instructor will give you background information on eutrophication and then you will get into groups. The instructor will assign each group a case study. Groups will read, discuss, and report out to the rest of the class on what can be learned from their case study.

References and Resources

Below are some resources you can use to learn more about Non-Point Source Pollution.

Diaz, R.J and Rosenberg, R., (2008). Spreading Dead Zones and Consequences for Marine Ecosystems, Vol. 321 no. 5891 pp. 926-929

Osmond, D.L., D.W. Meals, D. LK. Hoag, and M. Arabi, eds. (2012). How to Build Better Agricultural Conservation Programs to Protect Water Quality: The National Institute of Food and Agriculture–Conservation Effects Assessment Project Experience. Ankeny, IA: Soil and Water Conservation Society.

Committee on Environment and Natural Resources (2010), Scientific Assessment of Hypoxia in U.S. Coastal Waters. Interagency Working Group on Harmful Algal Blooms, Hypoxia, and Human Health of the Joint Subcommittee on Ocean Science and Technology. Washington, DC.

National Science and Technology Council (2003), An Assessment of Coastal Hypoxia and Eutrophication in U.S. Waters

US EPA, (2003), National Management Measures to Control Nonpoint Source Pollution from Agriculture EPA 841-B-03-004, July 2003

Gulfhypoxia.net website. Hypoxia in the Northern Gulf of Mexico

NOAA Hypoxia information website