Report to the Citizens of the Bay Region
-
www.chesapeakebay.net
Chesapeake Bay Program
A Watershed Partnership
CHESAPEAKE BAY
2006 Health & Restoration Assessment
Ecosystem Health
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Chesapeake Bay Program
A Watershed Partnership
CHESAPEAKE BAY
2006 Health & Restoration Assessment
The Chesapeake Bay Program is a
unique regional partnership that
directs and conducts the restora-
tion of the Chesapeake Bay by
bringing together local, state and
federal governments, non-profit
organizations, watershed residents
and the region's leading academic
institutions in a partnership effort
to protect and restore the Bay.
The Chesapeake Bay Program
signatories - the state of
Maryland; the commonwealths
of Pennsylvania and Virginia;
the District of Columbia; the
U.S. Environmental Protection
Agency representing the federal
government; and the Chesapeake
Bay Commission representing
Bay state legislators - have
committed to reducing pollution,
restoring habitat and sustainably
managing fisheries since signing
the Chesapeake Bay Agreement
of 1983.
Subsequent agreements have
augmented the original program,
and most recently culminated
in signing Chesapeake 2000, an
agreement intended to guide
restoration activities throughout
the Bay watershed through 2010.
Chesapeake 2000 also provided
an opportunity for the headwater
states of Delaware, New York and
West Virginia to join in regional
efforts to improve water quality
of the Bay and its tributaries.
To learn more and find out how
you can help, visit the Chesapeake
Bay Program website at
www.chesapeakebay.net
Chesapeake Bay Program
410 Severn Avenue, Suite 109
Annapolis, Maryland 21403
800-YOUR-BAY
www.chesapeakebay.net
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ABOUT THIS REPORT
The Chesapeake Bay is an estuary - a place of transition between the land and the sea, where
incoming fresh water mixes with salty ocean water. The Chesapeake Bay is a productive ecosystem
and is the largest estuary in North America, home to more than 3,700 species of plants and animals.
A healthy Bay requires balancing the needs of the region's people and economy with the needs of
the Bay for clean waters and ample habitat for aquatic life. The goal of Bay restoration is to restore
this balance by reducing pollution, protecting critical habitat and ensuring sustainable populations
of fish and shellfish.
The Chesapeake Bay 2006 Health and Restoration Assessment is presented this year in two parts.
Part One: Ecosystem Health draws on the most up-to-date monitoring data gathered by Bay
Program partners to assess the overall health of the Bay ecosystem last year.
Progress toward a restored Bay is tracked with 13 indicators grouped in three priority areas that
represent major components of the Bay ecosystem. Quantitative restoration goals have been set for
most of these indicators. For each indicator, a chart shows, as a percent of the goal, current status
and a history of progress toward achieving the goal. A summary bar chart shows
the current status of each indicator with respect to its restoration goal.
Although there are a number of smaller-scale success stories, the overall ecosystem health of the
Chesapeake Bay remains degraded. For more than twenty years, restoration efforts have managed
to offset the impact of the region's growing population while making modest ecological gains in
some areas. Major pollution reduction, habitat restoration, fisheries management and watershed
protection actions taken to date have not yet been sufficient to restore the health of the Bay.
In Part Two: Restoration Efforts, key restoration actions are measured against long-term goals.
We hope that, by presenting data in this manner, watershed residents can better understand the
health of the Bay relative to what is needed for a balanced ecosystem.
Electronic versions of the Chesapeake Bay 2006 Health and Restoration Assessment reports can be
found at www.chesapeakebay.net/press.htm. For more information about the data, methodology
and restoration goals discussed in this report, please visit www.chesapeakebay.net.
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HEALTH ASSESSMENT SUMMARY
INTRODUCTION
The human population in the Chesapeake watershed is now
growing by more than 170,000 residents annually. The cumulative
impact of centuries of population growth (currently over 16 mil-
lion) and landscape changes has taken its toll. For over 20 years,
restoration efforts have been underway to reverse the decline of
the Chesapeake Bay's health. Progress is not calculated on a day-
to-day basis, but by using detailed scientific data that have been
carefully analyzed and interpreted; we can see changes in the
health of the Bay over time. Change is occurring, but slowly.
Water Quality - Most of the Bay's waters are degraded.
Algal blooms fed by nutrient pollution block sunlight from
reaching underwater bay grasses and can lead to low oxygen
levels in the water and fish kills in some areas. Sediment from
urban development, agricultural lands, as well as some natural
sources, is carried into the Bay and clouds its waters. Portions of
Chesapeake Bay tidal tributaries are contaminated with chemical
pollutants that can be found in fish tissue. In 2006, less than
one-third of Bay water quality goals were met.
Habitats and Lower Food Web - The Bay's critical habitats
and food web continue to be at risk. Nutrient and sediment
runoff have harmed bay grasses and bottom habitat, while
disproportionate algae growth has pushed the Bay food web
out of balance. Currently, the Bay's habitats and lower food web
are at about one-third of desired levels.
Fish and Shellfish - Many of the Bay's fish and shellfish popula-
tions are below historic levels. Blue crab abundance has been
below management targets for the past ten years. American
shad are recovering slowly, while other species like striped bass
(rockfish) show mixed signals. The striped bass population has
increased over the past decade in the Chesapeake Bay. Scientists
attribute the increase to responsible fisheries management.
While biomass remains high, scientists are concerned about
the species' health.
As ecosystem-based goals are not yet developed for
menhaden, those data are not included in the average this year.
Currently, the Bay's fish and shellfish are at about two-fifths of
desired levels.
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SUMMARY: 2006 BAY HEALTH ASSESSMENT
Priority Areas
Water Quality
Percent of Goal Achieved
0 10 20 30 40 50 60 70 80 90 100%
Dissolved Oxygen
Mid-Channel Clarity
Chlorophyll a
Chemical Contaminants
Habitats and
Lower Food Web
Oyster
Susquehanna Shad
Menhaden
-
j
Not quantified in relation tc
a goal
Data and Methods: www.chesapeakebay.net/assess/methods
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DISSOLVED OXYGEN
Percent of Bay
Meeting Guideline
37%
of Goal Achieved
Data and Methods:
.chesapeakebay.net/access/methods
MID-CHANNEL WATER CLARITY
ercent of Bay
eeting Guideline
so
40
30
7%
of Goal Achieved
Data weighted by r
Data and Methods:
spective salinity zone.
www.chesapeakebay.net/as
WATER QUALITY
To support a vibrant Chesapeake Bay ecosystem, waters must
become clearer, oxygen levels higher, and the amount of algae
and chemical contaminants in its waters must be reduced. Water
Quality goals in this section are based on published water qual-
ity criteria designed to protect aquatic life in the Bay. Rain in the
winter and spring washes pollutant loads into the Bay, largely
determining summer water quality conditions. Summer weather
plays a role as summer storm intensity leads to greater erosion
and nutrient load. The health of the Bay in the critical summer
season will improve as actions are taken year-round to reduce the
level of pollutants in the watershed.
DISSOLVED OXYGEN
Like terrestrial animals, the Bay's fish and shellfish need oxygen
to survive. During summer months, some of the Bay's waters still
do not hold enough oxygen to support aquatic life. Throughout
summer 2006, scientists estimate about 37 percent of the Bay
met dissolved oxygen restoration goals designed to protect
resident aquatic life.
Over time, large-scale reductions in the amount of nutrients
flowing into the Bay will help improve low oxygen conditions.
MID-CHANNEL WATER CLARITY
Good water clarity is important for the growth of underwater
bay grasses. Because bay grasses provide vital habitat for a num-
ber of living resources in the Bay, it is essential to maintain good
water clarity and restore bay grasses to historical levels.
In 2006, scientists estimate that only 7 percent of the Bay's
waters had acceptable water clarity. Measurements for this indi-
cator are from fixed stations located in open water areas of the
Bay and do not necessarily reflect water clarity in shallow water
areas where bay grasses are most abundant.
Clarity will always fluctuate annually, as it is greatly impacted
by weather events; however, reduced nutrient and sediment
loads, abundant bay grasses and healthy Bay life will help
improve annual conditions.
DISSOLVED OXYGEN:
The amount of oxygen dissolved
in a stream, river, lake or bay is an
indication of the degree of health of
the water and its ability to support a
balanced aquatic ecosystem.
Source: EPA
CHESAPEAKE BAY 2006 Health & Restoration Assessment — PART ONE: Ecosystem Health
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CHLORPHYLL a
Scientists measure the amount of chlorophyll a in the Bay's
waters to assess the amount of algae present. The Bay needs the
right amount of algae to maintain a balanced food web. Excess
algae can cause large-scale algal blooms that block sunlight
from reaching bay grasses, reducing available habitat for Bay life.
Lower algal levels promote better water quality, more available
habitat and fewer harmful bloom effects.
Every year harmful algal blooms cover a portion of the Bay and
its tributaries. In 2006, scientists estimate that about 26 percent
of the Bay's waters had acceptable chlorophyll a concentrations.
CHEMICAL CONTAMINANTS
Portions of Chesapeake Bay tidal tributaries are contami-
nated with chemical pollutants that can be found in fish tissue.
The states and the District of Columbia use this information to
develop risk assessments and fish consumption advisories to
protect the health of recreational fishermen and their families.
Listings for all toxic contaminants in fish tissue were considered.
Ultimately this indicator is comprised of impairments due to
PCB tissue concentrations in Maryland and Virginia and mercury
tissue concentrations in Virginia, as these are currently the only
contaminants responsible for listings fitting criteria for inclusion in
this indicator.
Surveys indicate that in 47 percent of monitored tidal rivers
of the Bay, levels of bio-accumulative contaminants in fish tissue
are low enough for unlimited fish consumption. The remaining 53
percent of the monitored tidal rivers contain elevated contami-
nant levels that warrant advisories limiting the consumption of
fish from those waters.
The data used in this indicator was also used by the states of
Virginia and Maryland to determine fish tissue impairments for
the 2006 impairment listing. Some of the 2006 listings were first
determined during the 2002 listing cycle, which used data begin-
ning in 1996. Therefore, an eight year period is reflected in the
data. Prior to the 2006 listing year, there were insufficient spatial
data to allow the indicator to be developed, resulting in the
single point on the graph.
CHEMICAL CONTAMINANTS:
Substances, elements, or compounds
that may harm humans or other forms
of life if released into the environment.
Refers to concentrations that are above
acceptable levels and/or are in a loca-
tion where they should not be found.
Source: www.answers.com
CHLOROPHYLL a
Meeting Guidelines
26%
of Goal Achieved
Data and Methods:
.chesapeakebay.net/a:
CHEMICAL CONTAMINANTS
47%
of Goal Achieved
I
*lmp;
Data
nd Methods:
-accumulative contaminants in fish tissue for MD & VA
n. chesapeakebay.net/assess/methods
CHLOROPHYLL a:
The pigment that makes plants
and algae green. Measurement of
chlorophyll a is an indicator of the
quantity of algae in the water.
Source: EPA
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BOTTOM HABITAT:
HABITATS AND LOWER FOOD WEB
The bottom of the Bay is home to
bacteria, clams, worms and other
creatures that serve as a key food
source for higher levels of aquatic
life, such as white perch, spot,
croaker and crabs.
Source: Chesapeake Bay Program
BAY GRASS ABUNDANCE
Percent of
Goal Ach eved
ofG
90 -
80 -
70 -
60 -
50 -
40 -
so :
10 -
-V-
^_^^Xx'^J *\
32% 1 985 1990 1 995 2000 2005 201 0
oal Achieved
Data and Methods: www.chesapeakebay.net/assess/methods
BOTTOM HABITAT (Benthic Index of Biotic Integrity)
41%
of Goal Achieved
70
60
Baywide benthic monitoring program began in 1996
Data and Methods: www.chesapeakebay.net/assess/methods
Life in the Bay needs high-quality food and habitat to thrive.
From the clams and worms that live within the Bay's bottom sedi-
ments, to the rockfish that prowl its open waters, to the juvenile
fish and crabs darting among underwater grasses and wetlands,
healthy and abundant habitat is critical for supporting the Bay's
aquatic life. When healthy habitat is supported by a balanced
food web, healthy aquatic communities can flourish. As both
of these key environmental elements improve, the ecosystem's
potential to support larger and more diverse populations of
aquatic life expands as well.
BAY GRASSES
Aside from the water itself, underwater bay grasses are one
of the most important habitats in the Chesapeake Bay. As their
health is closely related to the quality of local waters, grasses
serve as an excellent barometer for the overall health of the
estuary. Bay grass abundance has a profound effect on the Bay
and its aquatic life, as it provides critical habitat to key species
such as striped bass and blue crabs while improving the clarity
of local waters.
The most recent baywide data from 2006 show bay grasses
covering 59,090 acres - or about 32 percent of the 185,000-acre
restoration goal.
The total Bay grass abundance goal has also been broken
down by 3 zones. Bay grasses in the Upper Bay in 2006 covered
15,510 acres or 66% of the 23,630-acre goal. Middle Bay grasses
covered 30,659 acres or 27% of the 115,229-acre goal, while
grasses in the Lower Bay covered 12,922 acres or 28% of the
46,030-acre goal.
As water clarity improves from nutrient and sediment pollution
reductions, bay grass acreage should expand.
BOTTOM HABITAT
The health of the Bay's bottom dwelling - or benthic - com-
munities is greatly reduced when pollution levels increase and
oxygen levels drop. Benthic habitats serve as a good indicator of
long-term environmental conditions, as the inhabiting worms and
clams are long-lived, have limited mobility and their responses to
stress are well documented.
6 CHESAPEAKE BAY 2006 Health & Restoration Assessment — PART ONE: Ecosystem Health
-------
In 2006, about 41 percent of the Bay's benthic habitat was
considered healthy as measured by the composite Benthic
Index of Biotic Integrity. Scientists attribute the decline from
2004 to persistent low dissolved oxygen levels during the
summer. Reduced amounts of nutrients, sediment and chemical
contaminants flowing into the Bay will help these bottom
dwelling communities improve.
PHYTOPLANKTON
Phytoplankton are an excellent indicator of the health of the
Bay's surface waters, as they are especially sensitive to changes in
nutrient pollution, water clarity, day length, temperature, salinity
and grazer communities. Phytoplankton are primary producers
capable of converting sunlight and nutrients into food for the
base of the food web.
While increased populations provide more food to organisms
further up the food web, too much or the wrong type of algae
can harm the overall health of the Bay. In some cases, harmful
algal blooms can impact human health.
Scientists assess microscopic algal community health with a
Phytoplankton Index of Biotic Integrity. Data from Spring 2006
show that about 31 percent of the Bay's phytoplankton communi-
ties were considered healthy.
TIDAL WETLANDS
Wetlands link land to the water. In both tidal and non-tidal
parts of the Bay, they serve as critical habitat to terrestrial and
aquatic life, and act as natural filters and sponges by absorbing
runoff and removing pollutants from water before they can reach
local streams and the Bay.
Many researchers believe Chesapeake Bay tidal wetlands are
threatened by sea level rise, storms, shoreline development and
invasive species. As of 1993, there were approximately 282,000
acres of tidal wetlands in the Bay. Assessments of acreage in
2001 and 2005 are pending data analysis.
For more information about wetland improvement efforts,
see page 7 of Part Two: Restoration Efforts.
PHYTOPLANKTON (Index of Biotic Integrity)
Percent of Bay
Meeting Guideline;
y
31%
of Goal Achieved
40
30
Data and Methods: www.chesapeakebay.net/assess/methods
PHYTOPLANKTON:
Microscopic plants such as algae
are capable of making food via pho-
tosynthesis. They float and cannot
move independent of water currents.
Source: EPA
TIDAL WETLANDS:
Wetlands that are tidally flooded
by salt or brackish water and are
found chiefly along the shores of
Chesapeake Bay and its tidal rivers.
Source: Chesapeake Bay Program
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A North American food and game
fish (Morone saxatilis) chiefly of
coastal waters, having dark longitu-
dinal stripes along its sides. Striped
bass, which swim up the Chesapeake
Bay to spawn, are occasionally found
in landlocked bodies of water. Also
called rockfish, striper.
Source: Chesapeake Bay Program
CHESAPEAKE BAY 2006 Health & Restoration Assessment — PART ONE: Ecosystem Health
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FISH AND SHELLFISH
The long-term health and sustainability of the Bay's fish
and shellfish is critical to restoring ecosystem health. Ample
aquatic habitat, clean water and well-managed fisheries are key
components to restoring abundant fish and shellfish populations
to the Bay.
Scientists and natural resource managers are working to
develop ecosystem-based fisheries management strategies which
take into account numerous factors when setting harvest targets,
including the species' role in the food web and other water
quality, habitat and climatic considerations. As these strategies
are further developed and ecosystem goals are defined, the Bay
Program will compare annual data to population targets for a
balanced Bay system.
BLUE CRAB
It is estimated that more than one-third of the nation's blue
crab catch comes from the Chesapeake Bay. Commercial harvest
from the Bay between 1968 and 2005 averaged around 73 million
pounds. The most recent harvests have been approximately 60
million pounds, or below the time series average. The low harvest
corresponds to low exploitable stock abundance and also reflects
restrictive management measures in place since 2001 and 2002.
In 2006, the abundance of adult crabs in the Chesapeake Bay
remained well below the restoration goal. Scientists estimate that
the population of blue crabs in the Chesapeake Bay in 2006 is
about 57 percent of the 232 million crab interim goal. Blue crab
abundance has been below the target for the past ten years.
These numbers are estimated through winter dredge and
summer trawl surveys. The blue crab fishery is vulnerable to
exploitation; therefore, harvest restrictions will continue to remain
in place. Proper management of the crab harvest, improved water
quality and habitat restoration efforts will help restore the Bay's
blue crab populations.
STRIPED BASS
The striped bass population has dramatically increased over
the past decade in the Chesapeake Bay. Scientists attribute this
increase to a late 1980s fishing moratorium and responsible
fisheries management since the lifting of the fishing ban. Striped
bass are one of the top predators in the Chesapeake Bay food
web and prey availability is an important factor affecting abun-
dance and growth. In 1995, populations had increased to the
point where the species was considered restored. While biomass
remains high, scientists are particularly concerned with the high
prevalence of disease (mycobacteriosis) and the ability of the
prey base to adequately support the population.
Research is underway to better understand the disease's
impact on the Bay's striped bass population. The current
status of Bay striped bass - high abundance but uncertain
health - illustrates the need for an ecosystem-based fisheries
management approach in Chesapeake Bay. The next assessment
of striped bass will take place during 2007.
For more information, see page 8 of Part Two:
Restoration Efforts.
BLUE CRAB ABUNDANCE (Age 1 and Older)
57%
of Goal Achieved
1985 1990 1995 2000 2005 2010
An abundance of 232 million crabs age 1+ is being considered as a management
target for Chesapeake Bay. This level of abundance would correspond with a level
of exploitation that preserves 20% of the blue crab spawning potential.
Data and Methods: www.chesapeakebay.net/access/methods
STRIPED BASS ABUNDANCE (Spawning Female Biomass)
100%
of Goal Achieved
1995 2000
Data and Methods: www.chesapeakebay.net/assess/methods
BLUE CRAB:
An edible, bluish swimming crab
(Callinectes sapidus) that has a wide
distribution in the Chesapeake Bay,
and along the Atlantic and Gulf
coasts of North America.
Source: Chesapeake Bay Program
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OYSTERS:
An edible bivalve mollusk of
the family Ostreidae, species
Crassostrea virginica, which lives
in a wide range of depths and
salinities of the Chesapeake Bay.
Source: Chesapeake Bay Program
OYSTERS
For more than a century, oysters constituted one of the Bay's
most valuable commercial fisheries. Over-harvesting, pollution
and the diseases Dermo and MSX have caused a severe decline
in their numbers throughout the Chesapeake Bay. Scientists
estimate that the population of native oysters in the Chesapeake
Bay in 2005 was about 9 percent of current restoration goals.
SHAD
The introduction of hatchery raised fish, a moratorium on shad
fishing, the removal of dams, and installation of fish passages on
key Bay tributaries have helped to increase the number of shad in
the Bay.
One of the ways scientists currently estimate spawning shad
populations is by counting the number offish annually lifted
over Conowingo Dam near the mouth of the Susquehanna River,
via the fish passageway installed in 1991. Annual estimates
have increased from several hundred per year in the early
1980s to 56,899 in 2006. In spite of the increasing abundance,
the Susquehanna River population is far below the long-term
restoration goal of two million fish per year.
Assessing annual baywide spawning populations is difficult as
each river stock is unique. To provide better baywide estimates,
scientists are developing new monitoring methods to estimate
populations in other key Bay tributaries including the James and
Potomac rivers. An updated assessment is expected in 2007.
ATLANTIC MENHADEN
Scientists currently do not produce Chesapeake Bay-specific
population estimates of menhaden. Estimates are made on an
Atlantic Coast-wide basis. Populations along the Atlantic Coast
appear to be healthy, but scientists are concerned about low
NATIVE OYSTER ABUNDANCE (Biomass)
Percent of
3oal Achieved
9%
90
80 -
70 -
60 •
50 •
40 -
30 •
20 •
10 -
1
•• - — *^-
985 1990 19?5 2000 2005 2010
of Goal Achieved Goal based on ten-fold biomass increase from 1994 baseline. 2005 data
point includes draft data from Virginia. The numbers will change over tim
Data and Methods: www.chesapeakebay.net/assess/methods
SHAD RETURNING TO THE SUSQUEHANNA RIVER
3%
of Goal Achieved
Based on Susquehar
Data and Methods:'
a River Restoration go
vw.chesapeakebay.ne1
regional abundances in Chesapeake Bay. The number of juvenile
menhaden in Chesapeake Bay has been declining in recent years,
with current recruitment levels being about 50% lower than the
mid-1980s.
In 2006, Virginia placed a cap on the amount of menhaden
that can be harvested annually from the Chesapeake Bay by the
commercial fishing industry. Maryland currently prohibits the
commercial industry from harvesting menhaden from Maryland
waters. Since menhaden are an important forage species in the
Bay food web, a number of studies are underway to assess their
status in the Bay.
AMERICAN SHAD:
The American shad, Alosa sapidissima, occurs along the Atlantic
coast from southern Labrador to northern Florida. American shad
undergo extensive seasonal migrations, moving into rivers for spawning
beginning in January in southern rivers, and continuing until July in
the northernmost portion of their range. After spawning, shad migrate
north along the coast to Canada where they feed during the summer. A
southward migration occurs later along the continental shelf where the
fish overwinter prior to spring spawning migrations to their natal rivers.
Source: NOAA
10
CHESAPEAKE BAY 2006 Health & Restoration Assessment — PART ONE: Ecosystem Health
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RIVER FLOW AND THE POLLUTANT
LOADS REACHING THE BAY
The Bay's watershed covers an enormous 64,000-square-mile
area that includes parts of six states - Delaware, Maryland, New
York, Pennsylvania, Virginia and West Virginia - and all of the
District of Columbia. Billions of gallons of water flow each day
through thousands of streams and rivers that eventually empty
into the Bay. The Bay must process runoff from a large amount of
land with a relatively small body of water.
Annual Bay water quality conditions are largely determined by
a combination of the amount of pollution deposited on the land
and the amount of water flowing into the Bay. As the river flow
increases, its potential to carry additional amounts of pollutants
multiplies as well.
Precipitation doesn't just increase river flows by washing
directly off the land. Some water seeps into the soil, carrying
nutrients into groundwater. It can take years for these waters and
their associated pollutants to slowly travel through underground
systems until they reach the streams that drain into the Bay. Each
year, pollution that may be decades old reaches the Bay.
Scientists calculate annual pollutant loads to the Bay through a
combination of monitored water samples and modeled informa-
tion. Whenever practical, scientists measure pollution levels in
water samples from the rivers and wastewater pipes that flow into
the Bay. Model generated estimates are used where monitoring
is not practical, when no data are available, or data do not meet
specific requirements and/or are outdated. By capturing water
samples at the point where large rivers meet the Bay, scientists
can calculate pollution loads from 78 percent of the watershed
land area. For the remaining area, loads from wastewater and
model-generated estimates are used. This combination of moni-
toring and modeling data allows scientists to provide the most
complete accounting of the amount of pollution reaching the Bay.
Spring 2006 weather conditions were considered extreme, with
lower than average rainfall from mid-February to mid-May. The
region was then deluged at the end of June with rainfall exceed-
ing the 100-year-flood mark in some areas. The remainder of
the summer weather was fairly average until August, when the
remnants of Hurricane Ernesto soaked the area.
Volume of water flowing into the Bay.
Source: Chesapeake Bay Program
ATLANTIC MENHADEN:
Brevoortia tyrannus are small school-
ing fish related to herring, shad, and
sardines. Menhaden consume large
quantities of phytoplankton and
zooplankton, and are themselves a
favorite food of striped bass, bluefish,
sea trout, tunas, sharks, and sea
birds. Menhaden spawn in the ocean,
in shelf waters off Chesapeake Bay
from March to May, and again in
September and October.
Source: VIMS
11
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RIVER FLOW AND NITROGEN LOADS
REACHING CHESAPEAKE BAY
Millions of
Pounds of Nitrogen
800 H
400-
Average Load
2006 data provision
Data and Methods:
Billions of
Gallons of Flow
1995 2000
w. chesapeakebay.net/assess/methods
RIVER FLOW AND PHOSPHORUS LOADS
REACHING CHESAPEAKE BAY
Millions of
Pounds of Phosphorus
60 '
Billions of
Gallons of Flow
Total river flow to the Bay during the 2006 water year (October
2005-September 2006) was very close to the long-term average.
Provisional estimates indicate that approximately 331 million
pounds of nitrogen reached the Bay during the 2006 water year,
which is similar to the average load for 1990-2005 and slightly
lower than 2005. This amount is almost double the restoration
target of 175 million pounds of nitrogen.
Additionally, provisional estimates indicate that approximately
13.4 million pounds of phosphorus reached the Bay during the
2006 water year, which is well below the 1990-2005 average and
almost half of 2005. This amount is above the target level of 12.8
million pounds of phosphorus to reach the Bay.
While less nitrogen and phosphorus reached the Bay during
the 2006 water year, additional pollution-fighting measures are
being put in place throughout the watershed to reduce total
pollution loads in the future.
Based on water samples collected at the point where large
rivers meet the Bay, in 2006 2.5 million tons of sediment were
delivered to the Bay. This is well below the average load for
1990-2005. The sediment load estimates do not account for
sediment from the coastal plain areas of the watershed. Scientists
are currently developing methods to quantify the total loads of
sediment to the Bay.
2006 data provisional.
Data and Methods: www.chesapeakebay.net/assess/methods
POLLUTANT LOAD
The amount of stress placed upon
an ecosystem by pollution, physical
or chemical, released into it by
man-made or natural means.
Source: General Environmenta
Multilingual Thesaurus (GEMET 2000)
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CHESAPEAKE BAY
WATE RS H ED
/mages: Bruce Fritz; Chesapeake Bay Program;
Chesapeake Bay Gateways Network; Mike Land;
Don Merritt©IAN Image Library; Donna Morelli;
National Aeronautics and Space Administration
(NASA); George Grall©National Aquarium in
Baltimore; National Oceanic and Atmospheric
Administration (NOAA); Jane Thomas©IAN Image
Library; United States Fish and Wildlife Service
(USFWS); United States Department of Agriculture
(USDA); Virginia Institute of Marine Science (VIMS)
This report was developed by the Chesapeake Bay Program partnership to help inform watershed
residents about the health of the Bay and efforts to restore it. Staff from a large number of state
and federal agencies, academic institutions and non-governmental organizations contributed
data and interpretation to the report, including The Alliance for the Chesapeake Bay, Chesapeake
Bay Commission, Del. Dept. of Natural Resources and Environmental Control, D.C. Dept. of
Health, Interstate Commission on the Potomac River Basin, Md. Dept. of Agriculture, Md. Dept.
of the Environment, Md. Dept. of Natural Resources, National Park Service, National Oceanic and
Atmospheric Administration, N.Y. Dept. of Environmental Conservation Old Dominion University, Pa.
Dept. of Conservation and Natural Resources, Pa. Dept. of Environmental Protection, Pa. Fish and
Boat Commission, Susquehanna River Basin Commission, University of Md. Center for Environmental
Science, University of Md. College Park, U.S. Army Corps of Engineers, USDA Natural Resource
Conservation Service, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, U.S.
Forest Service, U.S. Geological Survey, Va. Dept. of Environmental Quality, Va. Dept. of Conservation
and Recreation, Va. Dept. of Game and Inland Fisheries, Va. Institute of Marine Science, Va. Tech,
Versar, W.Va. Dept. of Agriculture and the W.Va. Dept. of Environmental Protection.
For a full list of contributing partners, visit www.chesapeakebay.net/baypartners.htm
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Chesapeake Bay Program
410 Severn Avenue, Suite 109
Annapolis, Maryland 21403
800-YOUR-BAY
www.chesapeakebay.net
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Printed on Recycled Paper
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U.S. Environmental Protection Agency
for the Chesapeake Bay Program
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