Order Code 98-869
CRS Report for Congress
Received through the CRS Web
Marine Dead Zones: Understanding the Problem
Updated September 20, 2006
Eugene H. Buck
Specialist in Natural Resources Policy
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress
Marine Dead Zones: Understanding the Problem
Summary
An adequate level of dissolved oxygen is necessary to support most forms of
aquatic life. Very low levels of dissolved oxygen (hypoxia) in bottom-water dead
zones are natural phenomena, but can be intensified by certain human activities.
Hypoxic areas are more widespread during the summer, when algal blooms
stimulated by spring runoff decompose to diminish oxygen. Such hypoxic areas may
drive out or kill animal life, and usually dissipate by winter.
The largest hypoxic area affecting the United States is in the northern Gulf of
Mexico near the mouth of the Mississippi River, but there are others as well. Most
U.S. coastal estuaries and many developed nearshore areas suffer from varying
degrees of hypoxia, causing various environmental damages. Research has been
conducted to better identify the human activities that affect the intensity and duration
of, as well as the area affected by, hypoxic events, and to begin formulating control
strategies.
Near the end of the 105th Congress, the Harmful Algal Bloom and Hypoxia
Research and Control Act of 1998 was signed into law as Title VI of P.L. 105-383.
Provisions of this act authorize appropriations through NOAA for research,
monitoring, education, and management activities to prevent, reduce, and control
hypoxia. Under this legislation, an integrated Gulf of Mexico hypoxia assessment
was completed in the late 1990s. In 2004, Title I of P.L. 108-456, the Harmful Algal
Bloom and Hypoxia Amendments Act of 2004, expanded this authority and
reauthorized appropriations through FY2008.
As knowledge and understanding have increased concerning the possible
impacts of hypoxia, congressional interest in monitoring and addressing the problem
has grown. The issue of hypoxia is seen as a search for (1) increased scientific
knowledge and understanding of the phenomenon, as well as (2) cost-effective
actions that might diminish the size of hypoxic areas by changing practices that
promote their growth and development. This report presents an overview of the
causes of hypoxia, the U.S. areas of most concern, federal legislation, and relevant
federal research programs. This report will be updated as circumstances warrant.
Contents
Introduction and Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Hypoxic Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Gulf of Mexico Dead Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Impacts of the Gulf of Mexico Dead Zone on Fishing . . . . . . . . . . . . . 6
Chesapeake Bay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Oregon Coast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Policy and Management Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Appropriations and Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
National Ocean Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Environmental Protection Agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Marine Dead Zones:
Understanding the Problem
Introduction and Background
Hypoxia refers to a depressed concentration of dissolved oxygen in water.
While definitions vary somewhat by region, it is generally agreed that hypoxia in a
marine environment occurs seasonally when dissolved oxygen levels fall below 2-3
milligrams per liter. Normal dissolved oxygen concentrations in nearshore marine
waters range between 5 and 8 milligrams per liter, and many fish species begin
having respiratory difficulties at concentrations below 5 milligrams per liter. In
extremely low oxygen environments, less tolerant marine animals cannot survive and
either leave the area or die.1 Mortality is especially likely for sedentary species. In
addition, spawning areas and other essential habitat can be destroyed by the lack of
oxygen. If these conditions persist, a so-called “dead zone” may develop in which
little marine life exists.2 The recovery of marine ecosystems following a hypoxic
event has not been extensively studied.
Decreased concentrations of dissolved oxygen result in part from natural
eutrophication when nutrients (e.g., nitrogen and phosphorus) and sunlight stimulate
algal growth (e.g., algae, seaweed, and phytoplankton), increasing the amount of
organic matter in an aquatic ecosystem. As organisms die and sink to the bottom,
they are consumed (decomposed) by oxygen-dependent bacteria, depleting the water
of oxygen. When this eutrophication is extensive and persistent, bottom waters may
become hypoxic, or even anoxic (no dissolved oxygen), while surface waters can be
completely normal and full of life. This is encouraged by rising bottom-water
temperatures in spring that stimulate increased decomposition by microbes, leading
to the development of bottom-water hypoxia.
Eutrophication occurs naturally when offshore winds or surface currents cause
cold, nutrient-rich, deep marine waters to rise near coasts, resulting in algal blooms
and natural hypoxic events. Many of the hypoxic events along the Pacific and
Atlantic coasts are caused by this natural upwelling. However, eutrophication can
be increased in intensity or frequency by nutrient loading from nonpoint sources (e.g.,
runoff from lawns and various agricultural activities including fertilizer use and
livestock feedlots), point-source discharge from sewage plants, and emissions from
vehicles, power plants, and other industrial sources.
1 Lisa A. Levin, “Oxygen Minimum Zone Benthos: Adaptation and Community Response
to Hypoxia,” Oceanography and Marine Biology: An Annual Review, v. 41 (2003): 1-45.
2 Some molluscs and annelid worms are more tolerant of low oxygen conditions and can
survive hypoxic episodes that last many weeks.
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Hypoxic zones frequently occur in coastal areas where rivers enter the ocean
(e.g., estuaries). Nutrient-rich fresh water is less dense than saltwater and typically
flows across the top of the sea water. The fresh surface water effectively caps the
more dense, saline bottom waters, retarding mixing, creating a two-layer system, and
promoting hypoxia development in the lower, more saline waters. In the northern
Gulf of Mexico, the greatest algal growth in surface waters occurs about a month
after maximum river discharge, with hypoxic bottom water developing a month
later.3 Hypoxia is more likely to occur in estuaries with high nutrient loading and
low flushing (i.e., low freshwater turnover).4 Human activities that increase nutrient
loading can increase the intensity, spatial extent, and duration of hypoxic events.
Storms and tides may mix the hypoxic bottom water and the aerated surface water,
dissipating the hypoxia.
Although the extent of effects of hypoxic events on U.S. coastal ecosystems is
still uncertain, the phenomenon is of increasing concern in coastal areas. Several
federal agencies are involved in analyzing the problem, including the U.S. Geological
Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA),
and the U.S. Environmental Protection Agency (EPA). Legislation was enacted by
the 105th Congress to provide additional authority and funding for research and
monitoring to address these concerns. This authority was extended by the 108th
Congress.
Hypoxic Areas
Hypoxic episodes have been recorded in all parts of the world, notably in
partially enclosed seas and basins where vertical mixing is minimal, such as the Gulf
of Mexico, Chesapeake Bay, the New York Bight, the Baltic Sea, and the Adriatic
Sea. In March 2004, the U.N. Environment Program’s Global Environment Outlook
(GEO) Year Book 2003 reported 146 dead zones where marine life could not be
supported due to depleted oxygen levels.5 Hypoxia is becoming more frequent and
widespread in these shallow coastal and estuarine areas.6 In addition, permanently
hypoxic water masses (i.e., oxygen minimum zones) occur in the open ocean,
affecting large seafloor surface areas along the continental margins of the eastern
Pacific, Indian, and western Atlantic Oceans.7
3 D. Justic et al., “Seasonal Coupling Between Riverborne Nutrients, Net Productivity and
Hypoxia,” Marine Pollution Bulletin, v. 26 (1993): 184-189.
4 R. Turner and N. Rabalais, “Suspended Particulate and Dissolved Nutrient Loadings to
Gulf of Mexico Estuaries,” in Biogeochemistry of Gulf of Mexico Estuaries, T. Bianchi, J.
Pennock, and R. Twilley, eds. (New York, NY: John Wiley & Sons, 1999), pp. 89-107.
5 See Box 4 at [http://www.unep.org/geo/yearbook/yb2003/089.htm].
6 R. J. Diaz and R. Rosenberg, “Marine Benthic Hypoxia: A Review of Its Ecological
Effects and the Behavioral Responses of Benthic Macrofauna,” Oceanography and Marine
Biology: An Annual Review, v. 33 (1995): 245-303. (Hereafter referred to as “Marine
Benthic Hypoxia.”)
7 John J. Helly and Lisa A. Levin, “Global Distribution of Naturally Occurring Marine
(continued...)
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About 21% to 43% of the area of United States’ estuaries have experienced a
hypoxic event; more than half of the affected area is in the Mississippi/Atchafalaya
River plume.8 In the Mid-Atlantic region, 13 of 22 estuaries have experienced
hypoxic/anoxic events.9 Of these, the Long Island Sound, Chesapeake Bay,
Choptank River, and the New York Bight experience the most serious annual
episodes. In the South Atlantic region, hypoxic/anoxic episodes are generally brief,10
with nearly two-thirds of this region’s 21 estuaries experiencing some hypoxia/
anoxia.11 The Gulf of Mexico region experiences the highest rate of hypoxic/anoxic
events, with almost 85% of this region’s 38 estuaries experiencing episodes of
hypoxia (including the Mississippi/Atchafalaya River plume).12 The North Atlantic
region is not as prone to hypoxic/anoxic events due to the generally low nutrient
input (the result of lower population density) and high tidal flushing. However, areas
adjacent to high population density (e.g., Cape Cod Bay and Massachusetts Bay) do
experience oxygen depletion. In the Pacific region, hypoxia also occurs near
population centers (e.g., San Diego Bay, Newport Bay, Alamitos Bay) or in areas of
limited circulation, even where water temperatures are cold (e.g., Hood Canal,
Whidbey basin/Skagit Bay).13
Gulf of Mexico Dead Zone
The hypoxic zone in the northern Gulf of Mexico is the largest observed in the
estuarine and coastal regions of the western hemisphere.14 First recognized in the
early 1970s, it is the largest and most hypoxic area in the United States. In the
summer of 1993, following massive Mississippi River flooding, the dead zone
covered more than 18,000 square kilometers (an area as large as the state of New
Jersey, although pockets of oxygenated water may occur within this boundary),
extending westward from the mouth of the Mississippi River to the upper Texas
7 (...continued)
Hypoxia on Continental Margins,” Deep-Sea Research, Part I, v. 51 (2004): 1159-1168.
8 N. Rabalais, “Oxygen Depletion in Coastal Waters.” NOAA’s State of the Coast Report.
(Silver Spring, MD: NOAA: 1998), National Picture, p. 4, [http://state-of-coast.noaa.gov/
bulletins/html/hyp_09/hyp.html]. (Hereafter referred to as “Oxygen Depletion in Coastal
Waters.”)
9 S. Bricker, “NOAA’s National Estuarine Eutrophication Survey: Selected Results for the
Mid-Atlantic, South Atlantic and Gulf of Mexico Regions,” Estuarine Research Federation
Newsletter, v. 23, no. 1 (1997): 20-21. (Hereafter referred to as “NOAA’s Estuarine
Eutrophication Survey: Selected Results.”); NOAA’s Estuarine Eutrophication Survey, vol.
1: South Atlantic Region (Silver Spring, MD: National Ocean Service, Office of Ocean
Resources Conservation and Assessment, 1996), p. 50.
10 “Oxygen Depletion in Coastal Waters,” Regional Contrasts, p. 2.
11 “NOAA’s Estuarine Eutrophication Survey: Selected Results,” pp. 20-21.
12 Ibid., pp. 20-21.
13 “Oxygen Depletion in Coastal Waters,” National Picture, p. 5.
14 N. Rabalais et al., “Consequences of the 1993 Mississippi River Flood in the Gulf of
Mexico,” Regulated Rivers: Research & Management, v. 14 (1998): 161-177.
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coast.15 The seasonal shape and extent of the dead zone are mostly a function of the
Mississippi/Atchafalaya River plume, the combined outflow from these two major
rivers, and the biological processes it influences. This hypoxic zone originates each
spring, as melting snow and peak runoff flush nutrients into the Mississippi River
system and eventually into the Gulf. The hypoxic zone generally occurs from May
to September, but varies from year to year. After reaching a maximum size of 20,000
square kilometers in 1999, the dead zone covered a much smaller 4,400 square
kilometers in 2000. Low velocity winds during the summer result in calm seas that
maintain the stratified barrier between surface and bottom water layers. Only during
weather disturbances, such as frontal passages, tropical storms, and hurricanes, does
vertical mixing of these stratified layers occur. Increased winds and frontal storms
in autumn vertically mix the water column, dissipating the hypoxia.16 In the summer
of 1998, this dead zone extended from very near shore (about 10-15 feet water depth)
to deeper waters than are normally hypoxic (as much as 160 feet deep off the
Mississippi River delta).17
Nutrient enrichment is the primary cause of eutrophication, of some algal
blooms, and of hypoxia, and is believed to be a major factor in areas such as the
northern Gulf of Mexico.18 The Mississippi watershed drains 41% of the land area
of the contiguous 48 states, including most of the farmbelt. Studies of the
Mississippi and Atchafalaya Rivers indicate that dissolved nitrogen levels have
tripled and phosphorus levels have doubled since 1960, fueling algal growth and the
resultant dead zone.19
Research suggests that fertilizer leaching and runoff from upriver agricultural
sources may be the main sources of nutrients. For example, USGS states that 56%
of the Mississippi River’s nutrient loading results from fertilizer runoff, with an
additional 25% of the Mississippi River nitrogen coming from animal manure
(municipal and solid wastes account for 6%, atmospheric deposition for 4%, and
unknown sources for 9%).20 Analysis of cores of sediments underlying the hypoxic
area reveals historic information on the Mississippi River watershed, indicating that
surface water productivity has increased and bottom water oxygen stress has
worsened since the early 1900s, with the most dramatic changes occurring since the
15 White House Office of Science and Technology Policy, Committee on Environment and
Natural Resources, Hypoxia Work Group, Gulf of Mexico Hypoxia Assessment Plan (March
1998), p. 3. (Hereafter referred to as “Hypoxia Work Group.”)
16 In August-September 2005, the winds from Hurricanes Katrina and Rita likely promoted
a somewhat earlier dissipation of the dead zone off the mouth of the Mississippi River.
17 N. Rabalais, press release, Louisiana Universities Marine Consortium (July 27, 1998).
18 Hypoxia Work Group, p. 2.
19 R. E. Turner and N. Rabalais, “Changes in Mississippi River Quality This Century —
Implications for Coastal Food Webs,” BioScience, v. 41, no. 3 (1991): 140-147; D. Justic
et al., “Changes in Nutrient Structure of River-Dominated Coastal Waters: Stoichiometric
Nutrient Balance and Its Consequences,” Estuarine, Coastal, and Shelf Science, v. 40
(1995): 339-356.
20 R. H. Meade, ed., Contaminants in the Mississippi River, 1987-92, Circular 1133 (Denver,
CO: U.S. Geological Survey, 1995), 140 pp.
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1950s — a change strongly correlated with increased use of commercial fertilizers
in the watershed.21 Although hypoxia occurred in the northern Gulf of Mexico prior
to heavy use of artificial fertilizers, human activities have exacerbated and prolonged
the hypoxic condition. Other studies also show a direct relationship between the
river-born nutrients, the high rates of phytoplankton production, and subsequent Gulf
of Mexico hypoxia.22 However, questions remain as to how much of the river’s
nitrogen might come from natural soil mineralization, what effects floods have on
nutrient transport, and how much nitrogen may be contributed by coastal land loss,
estimated at 25 square miles per year.23
Although studies have found that more than 70% of the total nitrogen
transported to the Gulf of Mexico by the Mississippi River originates above the
confluence of the Ohio and Mississippi Rivers,24 focusing on nitrogen runoff per unit
area identifies other areas where more concentrated nutrient runoff occurs.25
Although the lower Mississippi basin (which drains parts of Tennessee, Arkansas,
Missouri, Mississippi, and Louisiana) is responsible for only 23% of the nitrogen
delivered to the Gulf, some scientists believe that nitrogen removal and/or runoff
prevention strategies should focus on this area because of its much greater relative
nitrogen contribution26 and likely more economically efficient nitrogen removal.
21 T. A. Nelson et al., “Time-Based Correlation of Biogenic, Lithogenic and Authigenic
Sediment Components with Anthropogenic Inputs in the Gulf of Mexico NECOP Study
Area,” Estuaries, v. 17 (Dec. 1994): 873; B. J. Eadie et al., “Records of Nutrient-Enhanced
Coastal Productivity in Sediments from the Louisiana Continental Shelf.” Estuaries, v. 17
(Dec. 1994): 754-765; N. Rabalais et al., “Nutrient Changes in the Mississippi River and
System Responses on the Adjacent Continental Shelf,” Estuaries, v. 19 (1996): 386-407; S.
Gupta et al., “Seasonal Oxygen Depletion in Continental-Shelf Waters of Louisiana:
Historical Record of Benthic Foraminifers,” Geology, v. 24 (1996): 227-230; and R. E.
Turner and N. Rabalais, “Coastal Eutrophication Near the Mississippi River Delta,” Nature,
v. 368 (1994): 619-621.
22 F. H. Sklar and R. E. Turner, “Characteristics of Phytoplankton Production Off Barataria
Bay in an Area Influenced by the Mississippi River,” Marine Science, v. 24 (1981): 93-106;
S. E. Lohrenz, M. J. Dagg, and T. E. Whitledge, “Enhanced Primary Production at the
Plume/Oceanic Interface of the Mississippi River,” Continental Shelf Research, v. 7 (1990):
639-664; S. E. Lohrenz et al., “Variations in Primary Productivity of Northern Gulf of
Mexico Continental Shelf Waters Linked to Nutrient Inputs from the Mississippi River,”
Marine Ecology Progress Series, v. 155 (1997): 435-454.
23 D. Malakoff, “Death by Suffocation in the Gulf of Mexico,” Science, v. 281 (July 10,
1998): 190-192. (Hereafter referred to as “Death by Suffocation.”)
24 R. Alexander, R. Smith, and G. Schwarz, “The Regional Transport of Point and Nonpoint-
Source Nitrogen to the Gulf of Mexico,” Proceedings of the First Gulf of Mexico Hypoxia
Management Conference, Kenner, LA (Dec. 5-6, 1995), pp. 127-133 (hereafter referred to
as “Regional Transport”); R. H. Meade, ed., Contaminants in the Mississippi River, 1987-
92, Circular 1133 (Denver, CO: U.S. Geological Survey, 1995), 140 pp.
25 Of this total, 39% is contributed by the upper and central Mississippi River basins (which
include Minnesota, Wisconsin, Iowa, Missouri, and Illinois), 22% by the Ohio River basin,
and 11% by the Missouri River basin.
26 Nitrogen runoff for the lower Mississippi basin is 2,072 kilograms of nitrogen per square
(continued...)
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Researchers estimate that the benefits of nutrient controls in this lower basin could
be twice as effective as implementing them in upstream basins.27 Workshops and
conferences have identified strategies for implementing nutrient controls in the lower
Mississippi basin.28
Many farming interests maintain that evidence has not proven that agricultural
practices are the primary contributors to the development of the Gulf of Mexico dead
zone.29 Some farmers dispute that they contribute substantially to creating a dead
zone that is as much as 1,000 miles away. They argue that their goal is to keep as
much as possible of the applied nutrients on their land, since any nutrients that wash
away represent wasted money. On the other hand, it is estimated that as much as half
of the applied nutrients are lost to surface or ground water and to the air, resulting in
approximately $750 million in excess nitrogen (calculated as fertilizer cost) entering
the Mississippi River each year.30
Impacts of the Gulf of Mexico Dead Zone on Fishing. The Gulf of
Mexico supports important, easily accessible commercial and recreational fisheries,
bringing in almost $2.9 billion annually in retail sales to Louisiana and supporting
almost 50,000 jobs.31 These highly productive fisheries are the direct result of the
input of nutrients from the Mississippi River watershed. To date, no studies have
investigated the linkage between fishery declines and hypoxic episodes in the Gulf,
but some evidence suggests the dead zone may force fish and shrimp further offshore
as well as into shallow nearshore areas (producing what is locally called a “jubilee”)
that may provide less desirable habitat.32 Hypoxia increases stress on aquatic
ecosystems and may decrease biological diversity in areas experiencing repeated and
severe hypoxia.33 Crowding of marine life into restricted habitat also may lead to
indirect consequences through altered competition and predation interactions. In
26 (...continued)
kilometer per year compared to 708 kilograms of nitrogen per square kilometer per year for
the upper Mississippi basin and 437 kilograms of nitrogen per square kilometer per year for
the Ohio River basin.
27 “Regional Transport,” p. 131.
28 For example, see C. L. Cordes and B. A. Vairin, eds., Workshop on Solutions and
Approaches for Alleviating Hypoxia in the Gulf of Mexico, NWRC Special Report 98-02
(Lafayette, LA: U.S. Geological Survey, 1998), 53 p.
29 C. David Kelly, “Hypoxia Issue Paints a Murky Picture,” Voice of Agriculture, American
Farm Bureau (Sept. 29, 1997), at [http://www.fb.org/index.php?fuseaction=newsroom.
focusfocus&year=1997&file=fo0929.html].
30 “Death by Suffocation,” pp. 190-192.
31 Southwick Associates, The Economic Benefits of Fisheries, Wildlife and Boating
Resources in the State of Louisiana (Arlington, VA: March 1997), 21 pp.
32 Roger Zimmerman et al., “Trends in Shrimp Catch in the Hypoxic Area of the Northern
Gulf of Mexico,” Proceedings for the First Gulf of Mexico Hypoxia Management
Conference, Kenner, LA (Dec. 5-6, 1995), pp. 64-75.
33 “Marine Benthic Hypoxia,” pp. 285-287.
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addition, hypoxia may delay or impede the offshore migration of older, larger shrimp,
preventing shrimp trawlers from selectively targeting larger shrimp for harvest.
While it is unclear what specific effects the dead zone has on Gulf fisheries, the
occurrence of this dead zone may force fishing vessels to change their normal fishing
patterns, possibly expending more time and fuel to harvest their catch. One study has
concluded that any increase in fishing expenses could drive marginal operators out
of business. Other potential impacts on Louisiana fisheries include concentration of
fishing effort in other areas, resulting in localized overfishing; damage to essential
habitat, and possible decreased future production; shellfish mortality, if hypoxic
conditions impinge on barrier island beaches and coastal bay waters; localized
mortality of finfish and shellfish in shoreline areas; and decreased growth due to
reduced food resources in the sediments and water column.34 In August 1997, the
Louisiana Department of Wildlife and Fisheries initiated a three-year study, funded
by the National Marine Fisheries Service (NOAA, U.S. Department of Commerce),
to determine the dead zone’s impact on commercial fisheries.
Chesapeake Bay
Hypoxic conditions have been recognized in Chesapeake Bay for many years.35
In 2003, Virginia Institute of Marine Science scientists found a 250-square-mile area
of hypoxic water in upper Chesapeake Bay at depths below about 20 feet, from north
of Annapolis nearly to the mouth of the Potomac River. The low oxygen levels were
attributed to large nutrient inputs, likely carried into the bay by runoff from above-
average winter snowfall and spring rains. This runoff was able to pick up nutrients
that had accumulated in surrounding soils during four consecutive years of dry
weather.
Oregon Coast
Although permanently hypoxic water masses (oxygen minimum zones) affect
large seafloor surface areas along the continental margin of the eastern Pacific Ocean,
no dead zone events had been reported in the nearshore waters off the Oregon coast
prior to 2002. By 2006, the Oregon coastal dead zone was significantly larger,
thicker, longer lasting, and lower in oxygen concentration than previous years,
extending along the ocean floor from Cape Perpetua (Florence) in the south to
Cascade Head (Lincoln City) in the north, as close to shore as the 50-foot depth.36
34 J. Hanifen et al., “Potential Impacts of Hypoxia on Fisheries: Louisiana’s Fishery-
Independent Data,” Proceedings for the First Gulf of Mexico Hypoxia Management
Conference, Kenner, LA (Dec. 5-6, 1995), pp. 87-100.
35 Denise L. Breitburg, “Episodic Hypoxia in Chesapeake Bay: Interacting Effects of
Recruitment, Behavior, and Physical Disturbance,” Ecological Monographs, v. 62, no. 4
(1992): 525-546; James D. Hagy et al., “Hypoxia in Chesapeake Bay, 1950-2001: Long-
Term Change in Relation to Nutrient Loading and River Flow,” Estuaries, v. 27, no. 4
(2004): 634-659.
36 For more information, see [http://www.piscoweb.org/research/oceanography/hypoxia].
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The appearance and growth of this dead zone is attributed to fundamental, but not
well understood, changes in ocean conditions off the Oregon coast.37
Policy and Management Efforts
Since a temporary, yet severe, hypoxic event could result in significant mortality
or injury to marine mammals, fish, and other aquatic species, many have deemed
better understanding and consistent monitoring of hypoxic phenomena necessary.
NOAA initiated the Nutrient Enhanced Coastal Ocean Productivity (NECOP)
program in 1989 to study the effects of nutrient discharges on U.S. coastal waters.
This study found a clear link between nutrient input, enhanced primary production
(i.e., algal and plant growth), and hypoxic events in the northern Gulf of Mexico.38
In response to a January 1995 petition from the Sierra Club Legal Defense Fund
(currently known as Earthjustice Legal Defense Fund) on behalf of 18 environmental,
social justice, and fishermen’s organizations, the Gulf of Mexico Program39 held a
conference in December 1995 to outline the issue and identify potential actions.
Following that conference, Robert Perciasepe, Assistant EPA Administrator for
Water, convened an interagency group of senior Administration officials (the
“principals group”) to discuss potential policy actions and related science needs.
Subsequently, this “principals group” created a Mississippi River/Gulf of Mexico
Watershed Nutrient Task Force. Additionally, the White House Office of Science
and Technology Policy’s Committee on Environment and Natural Resources (CENR)
conducted a Hypoxia Science Assessment at the request of EPA. The CENR
assessment was peer-reviewed, made available for public comment, and submitted
to the task force to assist in developing policy recommendations and a strategy for
addressing hypoxia in the northern Gulf of Mexico.
In response to an integrated scientific assessment of hypoxia in the northern
Gulf of Mexico by the multi-agency Watershed Nutrient Task Force,40 a Plan of
Action for addressing hypoxia was released in January 2001.41 Estimates based on
water-quality measurements and streamflow records indicate that a 40% reduction
in total nitrogen flux to the Gulf is necessary to return to average loads comparable
to those during 1955-1970. Model simulations suggest that, short of this 40%
reduction, nutrient load reductions of about 20%-30% would result in a 15%-50%
increase in dissolved oxygen concentrations in bottom waters. Strategies selected
focus on encouraging voluntary, practical, and cost-effective actions; using existing
37 Brian A. Grantham, et al., “Upwelling-Driven Nearshore Hypoxia Signals Ecosystem and
Oceanographic Changes in the Northeast Pacific,” Nature, v. 429 (June 17, 2004): 749-754.
38 NOAA, Coastal Ocean Program Office, Nutrient-Enhanced Coastal Ocean Productivity,
Proceedings of 1994 Synthesis Workshop (1995), p. 119; see also Estuaries, v. 17, no. 4
(Dec. 1994): 729-911.
39 The Gulf of Mexico Program is a cooperative federal-state effort beginning after
Congress, through P.L. 102-178, designated 1992 as the Year of the Gulf of Mexico. For
additional information on this program, see [http://www.epa.gov/gmpo/].
40 See [http://www.nos.noaa.gov/products/pubs_hypox.html].
41 See [http://www.epa.gov/msbasin/taskforce/pdf/actionplan.pdf].
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programs, including existing state and federal regulatory mechanisms; and following
adaptive management. A reassessment of progress on implementing this action plan
was initiated in 2005.42
A key consideration is the level and duration of the necessary reduction in
excess nutrients from watersheds. Many agricultural lands have been saturated with
nutrients for many years, and it may take a long time to “cycle out” excess nitrogen
and phosphorus, even if application rates are reduced.43 While some believe this
problem may have no fast solutions and any management regime considered will
need to recognize that progress or improvement may not be apparent for years or
even decades, others suggest that improved agricultural practices in efficient
application of chemical fertilizers and prevention of soil erosion could yield
immediate and measurable benefits. Various policy options for modifying agriculture
practices continue to be discussed.44
Because nonpoint sources are major contributors to the problem at the mouth
of the Mississippi River system, many believe the Clean Water Act is the appropriate
legal framework for addressing future nutrient inputs. Under §319 of the Clean
Water Act, Louisiana and other states have initiated nonpoint-source45 control
programs. These programs seek to combine local, state, and federal agency resources
to address pollution from nonpoint sources within each state.46 To effectively address
concerns, however, nonpoint-source programs would need to be encouraged, funded,
and implemented throughout the Mississippi River watershed. Under §303 of the
Clean Water Act, states must identify water-quality-limited segments of their waters
that are not meeting standards, and then establish total maximum daily loads
(TMDLs) for each listed water and each pollutant (e.g., nutrients) that is not meeting
current water quality standards. In addition, agricultural research and educational
outreach/assistance to farmers might complement regulatory efforts.
Congress took note of the hypoxia problem in 1997 when the conference report
on FY1998 Department of the Interior appropriations (H.Rept. 105-337) directed the
USGS to give priority attention to hypoxia in its FY1999 budget. Near the end of the
105th Congress, provisions of the Harmful Algal Bloom and Hypoxia Research and
Control Act of 1998 were incorporated into the Coast Guard Authorization Act of
1998. This measure was signed into law as P.L. 105-383 on November 13, 1998;
Title VI authorized appropriations through NOAA to conduct research, monitoring,
42 See [http://www.epa.gov/msbasin/taskforce/reassess2005.htm].
43 “Death by Suffocation” (citing Don Goolsby, USGS, Denver, CO), pp. 190-192.
44 For example, see Suzie Greenhalgh and Amanda Sauer, “Awakening the Dead Zone: An
Investment for Agriculture, Water Quality, and Climate Change,” World Resources Institute
Issue Brief (February 2003), 24 p.
45 Originating from land use activities; sediment, organic and inorganic chemicals, and
biological, radiological, and other toxic substances are carried to lakes and streams by
surface runoff.
46 D. Sabin and J. Boydstun, “Louisiana Activities and Programs in Nutrient Control and
Management,” Proceedings of the First Gulf of Mexico Hypoxia Management Conference,
Kenner, LA (Dec. 5-6, 1995), pp. 196-198.
CRS-10
education, and management activities for the prevention, reduction, and control of
hypoxia, harmful algal blooms, Pfiesteria, and other aquatic toxins. In 2004, Title
I of P.L. 108-456, the Harmful Algal Bloom and Hypoxia Amendments Act of 2004,
expanded this authority and reauthorized appropriations through FY2008.
Appropriations and Funding
National Ocean Service. Hypoxia research is regularly funded through
appropriations to the National Ocean Service — part of the National Oceanic and
Atmospheric Administration in the Department of Commerce — in their Extramural
Research account under National Centers for Coastal Ocean Science. For FY2007,
NOAA requested $6 million for extramural research for grants related to harmful
algal bloom and hypoxia forecasting.
Agriculture. In the last few years, the U.S. Department of Agriculture’s
Cooperative State Research, Education, and Extension Service has provided a special
research grant of around $220,000 annually to Iowa State University’s Leopold
Center for Sustainable Agriculture for a project to define and implement new
methods and practices in farming that reduce impacts on water quality and the
hypoxia problem in the Gulf of Mexico.
Environmental Protection Agency. In the last few years, the Environ-
mental Protection Agency’s Environmental Programs and Management account has
provided a specific authorization of around $125,000 annually for the Missouri
Department of Agriculture’s Hypoxia Education and Stewardship Project. This effort
seeks to educate Missouri producers about hypoxia and encourage use of practices
that will reduce the amount of nitrogen lost through leaching and/or evaporation.