Chapter 18: Water Pollution
Saving the Bay: Teams of Researchers Try to Pin Down What’s Choking the Chesapeake
Story Abstract and Additional Information
This chapter examines the fact that water pollution decreases our usable water supplies, harms wildlife
and human life, and is largely caused by human actions. Some types of pollution may be easier to
address than others, but we can decrease pollution by protecting water bodies, restoring forested areas,
and limiting the use of potential pollutants.
Here are some of the key points in the story for this chapter:
What are some of the most common types of water pollution?

Over the decades, the Chesapeake Bay’s once-productive fisheries have crashed, and thriving
oyster beds that once lined the bottom of the bay have disappeared. These problems could be
traced back to water pollution—the addition of anything that might degrade the quality of the
water. The list of potential water pollutants is discouragingly long: industrial chemicals and raw
sewage get dumped directly into a body of water; garbage, oil, pesticides, fertilizers, and
sediments wash into water from the land; and contaminants such as mercury and acid, air
pollutants from fossil fuel combustion, fall back to Earth with the rain, much of it flowing as
runoff into rivers, streams, lakes, and seas. Read about how efforts to reduce pollution in the
bay have begun to pay off: http://articles.baltimoresun.com/2011-11-03/features/bs-gr-deadzone-20111103_1_dead-zone-pollution-chesapeake-bay.

In the Chesapeake area, runoff pollution floods the bay with an excess of nutrients, the first step
in a process known as eutrophication. Because the nutrients—primarily nitrogen and
phosphorus—fuel plant growth, extra amounts trigger explosions of algae, which block sunlight
from reaching underwater plants, causing them to die. Although the newly grown algae do emit
oxygen into the water as a by-product of photosynthesis, as a whole, less oxygen is produced
when the underwater plants die. As a result, levels of dissolved oxygen (DO) in the water
plummet—a condition known as hypoxia. Learn more from the World Resources Institute about
eutrophication and hypoxia: http://www.wri.org/project/eutrophication.
What is a watershed?

A watershed is the land area surrounding a body of water over which water—such as rain—
could flow and potentially enter that body of water. A variety of experiments have shown how
water flows through a watershed’s plants, soils, and streams. Some rainfall soaks into the soil,
infiltrating the ground below; some eventually reaches groundwater in the aquifer, which
people can tap into for a well. Learn more from the Environmental Protection Agency (EPA)
about the Chesapeake Bay watershed:
http://www.epa.gov/oaqps001/gr8water/xbrochure/chesapea.html.

If groundwater is deep enough, infiltration can act as a filtering system that purifies the water.
However, pollutants in heavily contaminated water can still make it all the way to groundwater
if the water table is close to the surface. For example, nitrate pollution from fertilizer runoff—
especially in regions of intense agriculture, like the midwestern United States—can contaminate
well water enough to be life threatening (children are most vulnerable). Read about how nitrate
pollution in groundwater is affecting residents in California's Central Valley farming
communities: http://openchannel.msnbc.msn.com/_news/2012/03/13/10657809-farmingcommunities-facing-crisis-over-nitrate-pollution-study-says.
How can we reduce water pollution?

The Clean Water Act, passed in 1972, regulates industrial pollution and sets pollution
standards—allowable levels of a pollutant that can be present in environmental waters or
released over a certain time period. Look up your community on the EPA website and learn
more about how the EPA is working with agricultural businesses in your area to reduce water
pollution: http://www.epa.gov/agriculture/whereyoulive.html.

A major component of restoration involves watershed management—managing what goes on in
the area around the streams and rivers. Read about new watershed management practices in
India that are helping farmers boost their crops:
http://knowledge.allianz.com/climate/mitigation_adaptation/?455/watershed-managementindia-smart-farming.
Additional information about other topics from this chapter:
Yard Chemicals

In suburban areas, lawns can be major nonpoint sources of nitrogen pollution if homeowners
apply too much fertilizer. You can play a role in reducing water pollution by decreasing your use
of chemicals (fertilizers, pesticides, harsh cleaners, etc.) that will end up in the water supply.
Learn more about alternatives to traditional yard chemicals at http://www.safelawns.org/.