X-/EPA
 United States
 Environmental
 Protection Agency
   The Gulf Dead Zone

  The Gulf of Mexico is the
  largest area of hypoxia
  in the United States. In
  the summer of 2002, the
  hypoxic zone measured
  larger than ever before.
  In fact, it covered an
  area greater than the
  size of Massachusetts.
  Hypoxia in the Gulf of
  Mexico has raised
  considerable concern
  throughout the United
  States because many
  people in coastal states
  make their livelihood
  fishing in the Gulf and
  many Americans
  vacation on the Gulf. It
  is also an indication of
  the quality of the waters
  that feed the Gulf,
  including the Mississippi
  River Basin.  The
  nitrogen concentration
  in Mississippi River Basin
  water has doubled since
  the 1950s.
What Is Hypoxia?
Hypoxia is the condition in which dissolved oxygen is
below the level necessary to sustain most animal life.
For many members of an aquatic community,
hypoxia is like drowning, because life-giving dissolved
oxygen levels in a body of water drop much lower
than normal. Hypoxia often occurs when high
concentrations of nutrients enter water as a result of
human actions.
1
   ust as on land, nutrients like nitrogen and
   phosphorus, which are found in fertilizer,
stimulate plant growth in water. In water, algae is
the predominant plant. Although algae is integral
to a healthy aquatic ecosystem, addition of
nitrogen and phosphorous beyond natural levels
can lead to the formation of large, unattractive
algal mats on the surface of lakes and algal
blooms in lakes and coastal waters. The
decomposition of algal blooms consumes
oxygen, and the resulting low oxygen condition,
or hypoxia, is inhospitable to many aquatic
organisms that then must flee or die.

Where Does Hypoxia Occur?
Hypoxia occurs throughout the world. In the
United States, the largest known area is off the
Louisiana Coast (see sidebar). Other known
areas in the United States are the Long Island
Sound and the Chesapeake Bay. Hypoxia can
    The six major sub-
    basins of the Mississippi
    River Basin and the Gulf of
    Mexico. Nutrients transported
    from  these areas contribute to
    Gulf of Mexico hypoxia.
occur naturally; however, there is no doubt that
human activites have increased the frequency,
areal extent, and severity of hypoxia around the
world. Although nutrient enrichment is the
primary contributor to hypoxia, landscape
changes such as the loss of coastal and
freshwater wetlands that naturally remove
nutrients from the water also contribute to the
problem. Many of the original freshwater
wetlands and riparian zones that were
connected to streams and rivers are now gone.

Mitigating Hypoxia Through
Wetland  Restoration
There is growing interest and expertise in the
field of wetland restoration. Federal, state,
tribal, and local agencies, as well as private and
nonprofit groups, are working not just to  slow
wetland loss, but to actually increase wetland
acres. This trend is good news for hypoxia-
affected waters since some wetlands can
significantly reduce the amount of nutrients
reaching our inland and coastal waters.
Restoring these wetlands can help reduce
nutrient loading to our nation's streams and
rivers. The following two examples highlight
such efforts.
                                                                                 Effects of Hypoxia
                                                • More expensive water treatment
                                                • Threat to commercial fisheries
                                                • Harmful algal blooms and shellfish
                                                 toxicity
                                                • Unattractive or smelly water
                                                • Fish kills
                                                • Damage to ecosystems and wildlife,
                                                 including "dead zones"
                                                • Decreased diversity of aquatic plant
                                                 and animal life

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Winter ricefield management protects the Gulf of Mexico from sediments and nutrients.
Iowa and the US Department of
Agriculture (USDA)
Iowa farmers, in coordination with USDA. are
presently hard at work creating and restoring
9,000 acres of wetlands that are strategically
located and designed to be especially effective
at removing nutrients and herbicides from
agricultural fields. Their project targets the
Raccoon River which produces one of the
highest nitrogen loads in the Mississippi River
Basin. Not only will this project improve
conditions in the Gulf of Mexico, but it will
also protect drinking water in Iowa.
                      Hunters Increase Wetland Acres
                      The conservation group Ducks Unlimited is
                      working with rice farmers to provide habitat
                      for migrating birds at a critical time of year.
                      Farmers flood their fields between crops
                      creating temporary wetlands that are needed by
                      the birds and that also reduce the
                      concentration of nutrients in runoff water.
                      Much of this same runoff water will finally
                      make its way to the Gulf less laden with
                      harmful concentrations of nutrients.  Ducks
                      Unlimited hopes to enroll 150,000 acres of
                      such wetlands in Arkansas alone.  This win-win
                      situation benefits farmers, waterfowl, and
                      downstream water users.
Restored Wetland in Northeastern Iowa
To protect your local waters and those downstream, you can
take some precautions:

1.   Use fertilizers on your farm prudently, and on your yard and
    garden sparingly or not at all. When you do use fertilizers, be
    sure to follow application time and amount recommendations
    closely. One useful tool to avoid over-applying (which can also be
    bad for plants) is a soil test. A test kit can be obtained from your
    local USDA extension office. Find yours at: www.reeusda .gov/
    1 700/statepartners/usa.htm
2.   Protect the wetlands and stream-side vegetation on your own
    property and in your community. Visit a wetland near your home
    and learn about its contributions to your local watershed.
3.   Help restore a wetland or a stream bank. Visit EPA's restoration
    website atwww.epa.gov/owow/wetlands/restore
4.   Properly maintain septic systems.
5.   Support local efforts  to reduce contamination of the water in your
    community. The first step is to determine the condition of water
    supplies and local streams in order to identify and then mitigate
    or eliminate sources of pollutants.
                                                                                            EPA843-F-02-002
                                                                                               Office of Water
                      For more information, call EPA's Wetlands Helpline at
                      1-800-832-7828, or visit www.eoa.gov/owow/wetlands
  Selected Refences:

  EPA's Mississippi River Basin Webpage	www.epa.gov/msbasin

  U.S. EPA 2001. National Coastal Condition Report. Office of Research and Development, Office of Water, U.S.
  Environmental Protection Agency, Washington, DC. EPA-620/R-01/005. www.epa.gov/owow/oceans/nccr
  CENR. 2000. Integrated Assessment ofHypoxia in the Northern Gulf of Mexico. National Science and Technology
  Council on Environment and Natural Resources, Washington, DC. www.nos.noaa.gov/pdflibrary/hypox final.pdf
  National Oceanic and Atmospheric Administration (NOAA).  1998. Oxygen Depletion in Coastal Waters by Nancy N.
  Rabalais. NOAAs State of the Coast Report. Silver Spring, MD: NOAA. state-of-coast.noaa.gov/bulletins/html/hyp 09/
  hyp, html

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