903R89101
The State of
the Chesapeake Bay
Third Biennial Monitoring Report -1989
U.S. Environmental Protection Agency
Region III Information Resource
Center (3PM52)
841 Chestnut Street
Philadelphia, PA 19107
I
TD
225
.C54
C246
1989
copy 2
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Foreword
1989 STATE OF THE BAY
U.S. Environmental Protection Agc
Region III Information Resource
Center (3PM52)
841 Chestnut Street
Philadelphia, PA 19107
The Participants.
This report was produced by the Data
Analysis Workgroup of the Chesapeake Bay
Program's Monitoring Subcommittee:
R. Magnien, Chair, R. Alden, R. Batiuk,
M. Burch, C. Heywood, F. Hoffman and
J. Mihursky.
Executive Editor/
Designer/Graphic Artist: Nina Fisher, CSC
Authors: Eric Barth
Richard Batiuk
Mary Jo Brown
Michael Burch
Diana Domotor
Nina Fisher
Frederick Hoffman
Jerrald Hollowell
Linda Hurley
Steve Jordan
George Krantz
Robert Magnien
Bruce Michael
Joseph Mihursky
Narendra Panday
James Uphoff
Gail Walton
Photos: M.E. Warren
Illustrators: A.J. Lippson, Elaine Kasmer,
Sue Armstrong
Monitoring Subcommittee
Robert Perciasepe, Chair, MD Dept. of the
Environment
Lee Zeni, Vice-Chair, Interstate Comm. on the
Potomac River Basin
Raymond Alden, Old Dominion Univ.
Richard Batiuk, U.S. Environmental Protection
Agency
Robert Bielo, Susqehanna River Basin Comm.
Mark Chittenden, VA Institute of Marine Science
Steve Funderburk, U.S. Fish & Wildlife Service
Carlton Heywood, Interstate Comm. on the
Potomac River Basin
Frederick Hoffman, VA Water Control Board
Steve Jordan, MD Dept. of Natural Resources
MONITORING—Webster defines it:" to watch, observe, or check especially
for a special purpose." For the Chesapeake Bay Program, the definition of
monitoring takes on additional dimensions—die long-term process of
collecting critical environmental data throughout a 66,500 square mile
ecosystem. Hundreds of individuals—scientists, managers, technicians and
citizens—from a multitude of agencies and institutions are involved in the
analysis and presentation of the information for management of this vast
watershed and tidal system. Insights into the state of the Bay and the future
course of management action are the culmination of mis process.
This complex array of people, stations, and data is yielding the information
necessary to support wise management decisions for Bay restoration. With
time, trends in water quality and shifts in plant and animal populations have
begun to evolve. Only now, with the trend information emerging, can we begin
to distinguish natural variability from man-induced changes—basic
information, yet critical to shape decisions for the Bay.
We know the ultimate goal—a balanced, productive estuary—and signs of
recovery are beginning to unfold. For the first time since Bay restoration
started, we have the substantial, high quality monitoring dam needed to move
forward into the next phase. Monitoring must not stop here. The growing base
of monitoring information will provide the means to continuously refine and
improve our stewardship of the Bay. There is no better means to accurately and
objectively evaluate what the Bay once was, where it now stands, and what
path it is traveling towards the future.
Chesapeake Bay Program Monitoring Subcommittee
Hamid Karimi, DC Environmental Control Div.
Dennis Lynch, U.S. Geological Survey
Robert Magnien, MD Dept, of the Environment
Samuel McCoy, National Oceanic and
Atmospheric Adm.
Joseph Mihursky, Chesapeake Biological Lab
Sheila Myers, Metropolitan Washington Council
of Governments
Bruce Neilson, VA Institute of Marine Science
Robert Pace, US Army Corps of Engineers
James Sanders, Benedict Estuarine Research
Lab
Dwayne Womer, PA Dept. of Envirornmental
Resources
The Chespeake Bay Program acknowledges
assistance and cooperation from the following:
Computer Sciences Corp., MD Dept. of the Envi-
ronment—Water Management Adm., MD Dept.
Natural Resources—Tidewater Adm., Old
Dominion Univ., PA Dept. of Environmental
Resources, Susquehanna River Basin Comm.,
U.S. Environmental Protection Agency-
Chesapeake Bay Liaison Office, U.S. Geological
Survey— Mid-Atlantic and PA Districts & Water
Resources Div. Hdqtrs., Univ. of MD—Chesa-
peake Biological Lab, VA Inst. of Marine Science
of the College of William & Mary, VA Marine
Resources Comm.— Fisheries Mngmt. Div.,VA
Water Control Board—Chesapeake Bay Office,
Environmental Research & Standards Office.
On the Cover _.
The front cover photograph was taken by M.E.
Warren in 1956 as he spent the day with the
Tidewater Fisheries patrol. The watermen are
dredging oysters under power just off Love Point
at the north tip of Kent Island. The three turn-of-
the-century skipjacks capture the Bay in one of
its most classic poses. Mr. Warren graciously
donated his photographs for use in this report.
(Archive # MdHR G 1890-25-12,664-20)
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able of Contents
1989 STATE OF THE BAY
Characterizing the Bay
• Monitoring the Bay
Ecosystem
• Monitoring
Programs
• How is the Bay Doing?
THE CHESAPEAKE
BAY ECOSYSTEM
USING MONITORING
FOR MANAGEMENT
The Bay's Rivers
• Draining the Land:
The Susquehanna River
• Road to Recovery:
The Upper Potomac
• Progress in the Patuxent
Managing Living Resources
• Bringing Back the
Striped Bass
• The Plight of the Oyster
• The SAV Link
Toxicant Case Studies
• The TBT Problem
• Kepone in the James
Towards the Future
• 1991 Nutrient Reduction
Strategy Reevaluation
* Developing Issues
FUTURE AND
DEVELOPING ISSUES
Printed on recycled paper
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Characterizing the Bay
1989 STATE OF THE BAY
Monitoring the
Bay Ecosystem
Like the Hopi Indian word portraying
life out of balance—koyannisqatsi— the
Chesapeake Bay is a system out of
balance. Those early benefactors of the
Bay, the Indians and colonists, found a
balanced, yet dynamic, Chesapeake,
Storms, seasonal warming and cooling of
the waters, rising and falling levels of
dissolved oxygen and fluctuating levels
of salinity and nutrients dictated the
daily, seasonal and yearly rhythms of the
Bay. Fish migrated in and out of its
waters sensing subtle temperature
changes while waterfowl foraged in the
rich Bay marshes and aquatic grasses
upon return from their northern breeding
grounds. Algae flourished with the
coming of spring but were held in check
by the millions of filter feeders, such as
oysters, that feasted on these tiny
floating plants. The Bay was constantly
changing yet maintained a delicately
balanced stance.
As more and more people inhabited
the Bay region, they cut the forests and
fished the waters more intently. Large
ships began to ply the waterways, homes
crowded along her shores and the Bay
became a receptacle for the wastes of our
growing society. Through the years, the
Bay played an increasing number of
commercial and recreational roles. It was
remarkably resilient in the early years of
exploitation—the bounties it could offer
seemed endless. Eventually, the
conflicting roles began to take their toll.
Harvests of finfish and shellfish
plummeted, the once flourishing
submerged sea grasses withered in the
turbid, nutrient-laden waters and toxic
"hotspots" have raised fears for the
health of the Bay and humans alike.
The degradation has not gone un-
noticed. Since the mid-1900s, scientists
and managers have attempted to unravel
the complexities of the Bay's decline. By
1984, the work had not only increased
but there began a concerted effort on the
part of the Bay states and jurisdictions to
pool resources and jointly tackle the
multitude of problems. In an attempt to
explain the stresses facing the
Chesapeake, recent research has
focused on the variety of interactions
among the physical, chemical and
biological components of the Bay. A
detailed picture of the energy pathways
moving through the system, from the
sun's energy to the high-level
consumers, is now emerging. Scientists
have also enhanced their understanding
of how man's activities interfere with
the natural flow of energy. This ex-
panded understanding allows us to
focus management and regulatory
efforts on Bay restoration while
increasing the yield of harvestable
resources.
One means to assess how much
living matter is produced in the Bay
and what pathways this "energy"
follows is to track the amount of carbon
in different groups of organisms. Car-
bon is one of the basic chemical "build-
ing blocks" of life. Figure 1 shows the
annual weight of carbon produced in
the mesohaline portion of the Bay. This
production is divided into plants (pri-
mary producers), zooplankton (small
floating animals), bottom-dwelling
animals (benthos) and fish within a
representative slice of the Bay's middle
zone. Even under natural conditions,
only a fraction of the plant production
eventually reaches the economically
important finfish and shellfish. The task
of managers is to restore the Chesa-
peake to a balanced ecosystem in which
as much of this energy as possible is
funneled into important and useful
biological yields— oysters, striped bass
and waterfowl, among others. In the
Bay's current condition, much of the
plant production does not reach these
higher levels but ends up decomposing
on the Bay bottom, robbing the water
of much needed oxygen.
Mirroring the complexities of the
Chesapeake Bay ecosystem, monitoring
is an intricate yet systematic process
designed to reveal the dynamics of the
Bay. Beginning in the outer reaches of
the watershed, researchers track and
measure the sources of nutrients and
other pollutants. Within the Bay, itself,
specialists monitor a variety of factors
to provide a comprehensive diagnosis
of the Bay's health. As data collection
continues, scientists unravel the techni-
cal details and translate the information
into terms meaningful to managers and
legislators who in turn implement
specific actions to remedy the Bay's
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ills. Citizens, informed of the monitor-
ing program findings, work within the
process by collecting supplemental data
for some of the programs. Their
involvement is critical: ultimately, it is
the citizens of the Bay region who will
pass judgment on the value of the Bay
and what we should spend to protect it.
Using Monitoring Information
Monitoring plays a key role in
guiding the Bay's restoration, making it
imperative that the information collect-
ed through the monitoring programs be
promptly and appropriately interpreted
and used. The first State of the Bay
report in 1985 introduced the newly
initiated Chesapeake Bay Monitoring
Program. The second report gave a
preliminary picture of the Bay
portrayed by the first two years of
monitoring data while elaborating on
the variety of projects under the
auspices of the Monitoring Program. In
this, the third report on the state of the
Bay, case studies depict the linkage
between long-term environmental
monitoring and Bay management,
providing an up-to-date diagnosis of
the Bay's health.
Figure 1
Fish
The Bay Pyramid
(Human
Activities)
0 1800 3600
Annual Production of Biomass
(1000's of metric tons of carbon in mesohaline Bay)
Decomposition
by Bacteria
Using these case studies, the report
demonstrates the progress and success-
es in using monitoring information for
specific management decisions that
have been made or will soon be
required. Some of these accounts rely
on data collected before many of the
recent programs started; they show
clearly the importance of a long-term
record. In these instances, we can
definitively state from where we've
come, where we are and where we're
likely to go in the future. Given many
of the uncertainties that still exist in our
understanding of the estuary, these case
studies teach important lessons. Un-
qualified successes documented by
monitoring programs in areas such as
the Potomac River, give us the
confidence to move forward with
similar management approaches in
other areas.
The prognosis for continued use of
monitoring information to support the
Bay restoration is excellent. Since
1984, the gaps in existing monitoring
programs have been closed. The
governors of the Bay states, the mayor
of Washington D.C. and the federal
government have committed to contin-
ued coordination of the bay wide
monitoring programs.
Monitoring spans the spectrum from
the policymakers to the individual
taking samples in the Bay. We are ap-
proaching a milestone in the latest Bay
Agreement where all relevant
monitoring information will be used to
scrutinize and reevaluate the current
baywide nutrient reduction strategy by
1991. This is a challenge that will test
the limits of the existing programs and
interjurisdictional coordination but is
certain to set a more confident course
for our management of the Bay.
Excess Nutrients: The Bay is suffering from
too much of a good thing. An overabundance
of nutrients, particularly nitrogen and phos-
phorus, kicks off a chain reaction in which
phytoplankton bloom, die off, sink and are
decomposed by bacteria. During decom-
position, the bacteria can use up much or all
of the dissolved oxygen, making it uninhabit-
able for most animals.
Sediments: Geologic processes generally
take place on a lengthy time scale. When man's
activities speed up processes such as erosion
of the shoreline and land, problems inevitably
result. Suspended sediment clouds the water
and decreases the amount of light able to reach
aquatic grasses. As the sediment settles, it
The Problems
may smother non-mobile shellfish, prevent
oyster spat from setting and after the type of
animal that can live on the Bay bottom.
Toxics: A toxic substance is any material which
is harmful or fatal to organisms. Scientists have
found high concentrations of numerous toxic
metals and organic compounds in the Bay water
and sediment, particularly in industrialized areas
such as the Patapsco and Elizabeth rivers.
These compounds can cause chronic or lethal
effects in the animals and plants.
Low Dissolved Oxygen: As a consequence
of nutrient overenrichment, the Bay's deep
bottom waters become depleted of dissolved
oxygen (DO) each summer. In the most severe
areas, no DO exists—a condition known as
anoxia. Without oxygen, almost all organisms
are driven away or die. Even low DO
conditions—hypoxia—severely stress Bay
animals.
Habitat Loss: As the Bay region has under-
gone development over the past centuries,
substantial habitat has been lost to the plow.
bulldozer and backhoe. While many habitats
have been lost outright, others have been
severely modified by the indirect impact of
these activities. Sediment running off the land
has dogged wetlands, turbidity and nutrient
overennchment have destroyed SAV and
accelerated erosion has destroyed shoreline
habitat.
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Monitoring Programs
Like analysts diligently tracking the
daily fluctuations and long-term trends
of the stock market, Bay scientists
monitor the Chesapeake Bay. Routine
collection and analysis of water samples
provide information on short and long-
term changes in water quality while the
status of the supporting members of the
estuarine food web—plankton, benthic
organisms and aquatic grasses—are
monitored as the primary indicators of
the Bay's biological health. Building on
a data base reaching back to the 1950s,
monitoring of the Bay's finfish and
shellfish populations provides the infor-
mation needed to ensure wise manage-
ment of existing living resources—the
ultimate measure of our success in
revitalizing the Bay. Monitoring serves
not only to assess the current "state of
the Bay" and long-term trends, but also
to help better understand its dynamics in
response to pollution reduction.
In 1984, state and federal agencies
initiated a coordinated monitoring
program in the Chesapeake Bay main-
stem and its tidal tributaries. Integrated
with this water quality network (50
mainstem, 40 Virginia tributary and 57
Maryland tributary stations) are plank-
ton, benthos and sediment sampling at
some of these stations. The Chesapeake
Bay Monitoring Program has since
expanded to include monitoring activi-
ties in the District of Columbia, other
living resource monitoring programs,
and monitoring of non-tidal Bay tribu-
taries. This section provides an over-
view of the Monitoring Program and
related Bay basin monitoring programs.
In August 1989, the Bay Program's
Monitoring Subcommittee published the
"Chesapeake Bay Basin Monitoring
Program Atlas," a document containing
summary descriptions of ongoing, long-
term environmental monitoring
programs within the watershed. The
number and diversity of monitoring pro-
grams described in the atlas attest to the
wealth of information being generated
for management purposes. Yet, the
sheer number of programs emphasizes
the need to integrate across jurisdiction-
al boundaries—in essence, to treat the
Chesapeake as a whole.
Physical Processes Monitoring
Precipitation has a tremendous in-
fluence on the Bay as a direct (atmos-
pheric) and indirect (runoff) source of
nutrients and toxicants. Through the
National Oceanic and Atmospheric
Administration's (NOAA) National
Climatic Data Network, researchers
sample 268 stations over the Bay basin
for key meteorological parameters.
Scientists use precipitation and climate
information for computer modeling and
to explain the relationship between land
use and nonpoint source pollutants.
Water Quality Monitoring
If the mainstem Bay is the lower
trunk of a large tree, then the freshwa-
ter streams and rivers are the vast
network of roots sustaining the tree.
Water and nutrients move through the
roots eventually finding their way into
the trunk. Monitoring in the "roots,"
extending into New York, West
Virginia and Delaware, provides valua-
ble infor-mation on their contribution
to the Bay's overall water quality.
Closer to the Bay, state monitoring
networks in Pennsylvania, Maryland
and Virginia track water quality trends.
In addition, the states concentrate
intensive nonpoint source sampling of
nutrient and pesticide loads in selected
watersheds. By monitoring water quali-
ty within a watershed, managers can
determine the contribution of pollutants
from all upstream sources. Monitoring
water quality where the free-flowing
river meets tidal waters provides a
measure of the total upstream load of
nutrients and toxicants moving into the
tidal waters. Baseflow and storms are
both monitored to characterize pollutant
loadings from point sources, ground-
water and nonpoint sources.
In all the Bay basin states, the U.S.
Geological Survey (USGS) maintains
networks of water quality monitoring
and streamflow gaging stations as pan
of a national program initiated in the
1890s. The USGS, Maryland and
Virginia cooperatively monitor water
quality, nutrients and metals at the fall
line. Technicians collect baseflow and
storm samples on the Susquehanna,
Patuxent, Potomac and Choptank rivers
in Maryland and on the James,
Appomattox, Pamunkey, Mattaponi and
Rappahannock rivers in Virginia.
All the states monitor municipal and
industrial point source dischargers
within their Bay basin jurisdictions.
Self-monitoring (performed by the
Water Quality Issues
of Concern
Management
Action
New or Revised
Management
Strategies
Management
Information Needs
Interpretation of
Available Information
Monitoring Program
Design
Monitoring Program
Results
Monitoring Program
Implementation
Figure 2. Sequence of steps linking management and monitoring. When the loop
between the water quality issues that led to the development of the monitoring pro-
gram and the resultant management actions closes, the program has realized its goal.
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discharger) and compliance monitoring
(performed by the states) provide man-
agers with detailed estimates of point
source toxicants and nutrient loads.
As nutrients and suspended sedi-
ments enter the tidal Chesapeake Bay,
state monitoring programs measure
their impact on estuarine water quality.
Closely coordinated with fall line and
nontidal tributary monitoring, these
programs identify the sources of
pollutants, the fate of these pollutants
and their impact on habitat quality.
Reduction targets can then be estab-
lished based on the source and
characteristics of individual pollutants.
Through joint state and federal
funding, Maryland and Virginia have
monitored water quality at 50 stations
throughout the Bay's mainstem since
1984. At the same time, these states
have sampled a network of tidal tribu-
tary water quality stations. Water
quality monitoring of the Potomac and
Anacostia rivers within the District of
Columbia has continued since a similar
network was established in 1979. Com-
parable field, analytic and data manage-
ment techniques allow the compilation
of these data on a centralized computer
database in Annapolis, Maryland. Other
important data used in the Bay analyses
include the basinwide Citizen Monitor-
ing Program which brings volunteers
into the monitoring of Bay water
quality. Engineers, farmers, retirees,
students and others sample the Cones-
toga, Patuxent, Choptank, James and
other rivers on a weekly basis.
Living Resources Monitoring
As Bay water quality improves,
beneficial changes in the species form-
ing the food web base will signal a re-
turn to a dynamically balanced estuary
capable of sustaining healthy plants and
animals. Maryland, Virginia and the
District of Columbia all monitor the
composition, abundance and distribu-
tion of phytoplankton, zooplankton and
benthic organisms at a subset of the
Bay water quality monitoring stations.
Aquatic grasses provide a strong
link between improved water quality
and recovery of the Bay's living re-
sources. Given their importance as food
and habitat, they are a key barometer of
Bay health. The baywide aerial survey
program, initiated in 1978, has
documented recent increases in the
distribution and abundance of
submerged aquatic vegetation (SAV).
Field surveys and water quality
monitoring in SAV beds complement
the aerial survey program, using state
and university personnel as well as
watermen and citizen volunteers.
At the higher levels of the food
web, monitoring becomes progressively
more difficult A variety of factors
combine to influence the health and
status of the finfish and shellfish—
harvest pressure, eutrophication, food
availability, climatic events and habitat
Examples of Other
Monitoring Programs
Within the Bay Basin
Add Deposition - Maryland Acid
Precipitation Monitoring Program
Air Quality - New York Air Quality
Monitoring Program
Groundwater - West Virginia
Observation Well Network
Habitat Monitoring - Maryland Striped
Bass Habitat Monitoring Program
Lake Monitoring - Virginia Lake
Monitoring Program
Nonpoint Source Monitoring • Virginia
Nomini Creek Watershed Moni-
toring Program
Radiology - Pennsylvania Radiological
Monitoring Program
Special Coordinated Programs -
Coordinated Anacostia Monitoring
Program
Special Toxics Monitoring - Virginia
Kepone Finfish Monitoring Program
Utility Supported - Philadelphia Electric
Co., Susquehanna River Water
Quality Monitoring Program
change. The finfish and shellfish
monitoring programs are evolving to
provide the understanding of fish
populations needed for management.
Under a program initiated in 1939,
Maryland monitors oyster spat and
condition at bars in the northern Bay
each fall. Virginia conducts spring and
fall surveys of oyster bars, spatfall
counts and disease surveys at selected
stations throughout the lower Bay. As
oyster numbers continue to decline
under harvest pressures and increased
prevalence of disease, data are needed
to manage the state oyster repletion
program and regulate annual harvests.
As recreational and commercial
harvests of blue crabs increase, impacts
on the crab populations will continue to
be monitored. Maryland monitors the
seasonal abundance of adult blue crabs
while Virginia tracks the abundance of
larvae and juveniles.
Maryland, Virginia and the District
of Columbia monitor the abundance
and distribution of finfish through seine
and trawl survey programs. Managers
use this information is used to oversee
current fishery stocks. They also use
the long-term data records, along with
other information, to evaluate the
effectiveness of habitat restoration
initiatives and to target pollution
abatement programs.
In Maryland, surveys of nearshore
fish populations in the upper Bay and
the Choptank, Nanticoke, and Potomac
rivers began in 1954. Scientists survey
juvenile river herring populations in the
upper tidal tributaries from June to
September. American shad populations
have been monitored in the upper Bay
since 1980. Maryland's Adult Striped
Bass Survey includes sampling at over
60 non-fixed stations throughout the
northern Chesapeake Bay.
The District of Columbia's two
finfish programs survey anadromous
and resident finfish on the Potomac and
Anacostia rivers. Under Virginia's
juvenile finfish survey program, the
state has assessed the current status and
long-term trends of Virginia's juvenile
finfish populations in the James, York
and Rappahannock rivers since 1954.
In these same rivers, the state has also
used beach seine surveys to evaluate
juvenile striped bass populations.
Juvenile herring and shad populations
are surveyed at stations located on the
Mattaponi and Pamunkey rivers to
monitor year class strength.
Given the importance of the Chesa-
peake region as part of the Atlantic
Flyway for migratory waterfowl as well
as the Bay's abundant habitats for
resident song, wading and shorebirds,
there is a strong focus on monitoring
bird populations. The U.S. Fish and
Wildlife Service (USFWS) estimates
populations through its annual Chesa-
peake Bay midwinter waterfowl
survey. Using volunteers, the National
Audubon Society conducts a December
bird count throughout the basin as part
of a nationwide program and USFWS
volunteers annually survey waterfowl
breeding. Pennsylvania and Maryland
also administer annual waterfowl
breeding surveys. Maryland and Vir-
ginia participate annually in a bald
eagle survey and Virginia regularly
monitors its populations of ospreys and
colonial birds.
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Toxicants Monitoring
Contaminants in sediments and
animals pose hazards to other Bay
animals and man as these substances
migrate through the food web. In their
tidal waters, Maryland and Virginia
analyze sediments every 3-5 years for
contaminant levels. State and federal
programs ensure that the Bay's shellfish
and finfish are safe for consumption.
Under the EPA's national contami-
nant monitoring program, finfish tissue
contaminant levels are monitored in
Pennsylvania, Maryland, the District of
Columbia, Virginia and West Virginia.
The USFWS maintains stations on the
Susquehanna, Potomac and James rivers
under its national pesticide monitoring
program. NOAA also monitors shellfish
and finfish tissue contaminants as part
of its National Status and Trends
Program. Scientists use these data to
compare the status of the coasts and
estuaries bordering the nation.
How is the Bay Doing?
The most commonly asked question
of anybody working on the restoration of
the^Chesapeake Bay is apparently
simple—"How is the Bay doing?" It's not
an easy question. The Bay is suffering
from a variety of maladies. The answer
depends on the specific problem. Some
remarkable achievements have been
made on many of the problems—yet
there is much left to accomplish.
Pictures have a way of translating
information in ways that words cannot.
The following section relies primarily
on illustrations to spell out the many
states of the Chesapeake Bay.
The Unseen Contaminants
PAHs in the Sediment
Metals in the Sediment
10000 8000 6000 4000 2000 0
parts per billion
Monitoring of sediment contami-
nants is critical to track regional trends,
understand potential toxic impacts to
Bay resources and make dredging deci-
sions. The sediments provide both short
and long-term memory of contaminant
loadings to the Bay. This information
allows scientists and managers to locate
hot spots and analyze the effectiveness
of our efforts to reduce and eliminate
20 40 60
parts per million
80
the discharge of toxicants to the Bay.
From Susquehanna Flats south to the
Bay mouth, polynuclear aromatic hy-
drocarbons (PAHs) show a significant
concentration gradient The highest
concentrations of PAHs range from just
south of the Sassafras River (the main-
stem's turbidity maximum) to south of
the Bay Bridge. A second spike in con-
centrations shows up at the mouth of
the James River, adjacent to the indus-
trialized Elizabeth River. Sediment
levels of metals (averaged for 1984 and
1985) peaks off the Patapsco River and
gradually decline down Bay until high
levels are again seen off the James. The
sources of these contaminants are
combustion of fossil fuels (PAHs), in-
dustrial point sources, urban runoff and
upstream sources (metals).
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1984
1987
Regions of the Bay's bottom water
whiefc become afoxic (lac* of oxygen
in the water • ) and hypoxic (oxygen
levds'te^^'titep^ ingi Q) during the
summer months are displayed above.
Tracking
Dissolved
Oxygen in
Chesapeake Bay
1985
The Importance
of Dissolved Oxygen
Maryland Water _
Quality Standard
Virginia Water _____
Quality Standard
Minimum level for _
long-term oyster
survival
Phosphorus released
from sediment
Hydrogen sulfide
production
1
0.5
OS
0
DO Concentrations
Hypoxla
1986
1988
Low oxygen conditions not only stress
the toy's living ^|o*ces,%mtp^!t ,
cause production «f f«sie fefA^p.
phorus from the bottom seMM&»,
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Dissolved Oxygen in the Chesapeake Bay
Restoration of dissolved oxygen
(DO) to levels required by the Bay's
living resources is a central goal of the
Chesapeake Bay Program. Through
monitoring, scientists and managers
have tracked monthly, seasonal and
annual changes in the spatial, temporal
and volumetric extent of DO through-
out the Bay since 1984. Spatial data
shown in the preceding maps and
corresponding volumetric data on the
bar graph are based on the worst DO
conditions of each summer. The
descriptions below detail the dramatic
differences between years which give
testimony to the influence of the
climate on DO patterns.
In 1984, riverflow into the Bay was
well above normal during the winter
and spring, contributing large nutrient
loads and decreasing surface water
salinity. These factors caused increased
stratification (layering) which resulted
in a long stretch of oxygen-depleted
waters near the bottom of the Bay.
Below average river flows trans-
lated to reduced nonpoint source
nutrient loads and higher surface
salinities in 1985. The region of low
DO was confined to the area extending
from south of the Bay Bridge to the
mouth of the Potomac River.
From 1986 through 1988, riverflows
remained below normal due to lower
than average precipitation in the Bay
region. Stratification of the water
column was sufficient during the early
part of each summer to cause anoxic
conditions from north of the Bay
Bridge to just south of the Patuxent
River. The anoxia, however, did not
extend into Virginia waters as occurred
in 1984.
Differences in the total volume of
low DO waters between years is largely
due to early summer meteorological
events, the volume of riverflow coming
into the Bay each year and the resultant
intensity of water column stratification.
250-1
1984 1985 1986 1987 1988
DO in milligrams/liter
0-0.2 0.2-2.0 [~~l2-5
Volumes of anoxic (0-0.2) and
hypoxic (0.2-2.0) waters in the main
Bay as well as waters not meeting state
water quality standards (2-5) for DO.
The total volume of water in the main
Bay is 579 (x 100 million) cubic meters.
The Waterfowl Picture
2500
D Canada Goose
El Canvasback
Divers
Dabblers
1936 1941 1946 1951 1956 1961 1966 1971 1976 1981
Waterfowl, heavily dependent on SAV
and several species of invertebrates for
food, have been hard hit by nutrient
enrichment and toxicant contamination
which have degraded the supply of
these once abundant foods. The plot of
Bay and tributary waterfowl from 1936
to 1987 displays overall reductions in
the duck population and an increase in
geese stocks. Dabbling ducks such as
the mallard, black duck and pintail
have fallen from 42% to 12% of the
Bay's waterfowl population and diving
duck abundance has diminished from
40% to 11%. Over the same period of
time, canvasback ducks have remained
fairly stable with peaks in the early
1940s and mid-1950s while Canada
geese have risen from 11% to 68% due
to the ability to shift their feeding to
grains left in the field after harvest.
Overall duck numbers likely will remain
low unless their primary food supplies
are restored to more abundant levels.
-------
Nutrients and Chloroph
SUSQUEHANNA
Nitrogen
Total nitrogen measured in milli-
grams per liter for Chesapeake Bay
segments based on salinity and
circulation zones (tidal fresh, riverine-
estuarine transition, lower estuarine).
Year- round Maryland and Virginia
tributary and mainstem monitoring data
NORFOLK
from 1984-1988 was averaged to obtain
each value. Higher nitrogen concen-
trations generally occur in the tidal
fresh zones, gradually decreasing in the
more saline waters found in the tribu-
taries' lower estuarine reaches and the
southern portion of the Bay.
SU'
Phosphorus
BALTIMORE
0.16 -1
0.08 -
0.00
024
WASHINGTON
DC •.;-':'•.;.•.)
0.16
0.08
000
Total phosphorus measured in milli-
grams per liter for Chesapeake Bay seg
merits based on salinity and circulation
zones (tidal fresh, riverine-estuarine
transition, lower estuarine). Year-
round Maryland and Virginia tributary
8
-------
/ in the Chesapeake Bay
ANNA
008
mainstem monitoring data from
4-1988 was averaged to obtain each
ue. Higher phosphorus concentra-
s generally occur in tributaries
ich are in close proximity to point
nonpoint sources of this nutrient.
80-1
60-
SUSQUEHANNA
Chlorophyll
Active chlorophyll measured in
micrograms per liter for Chesapeake
Bay segments based on salinity and
circulation zones (tidal fresh, riverine-
estuarine transition, lower estuarine).
Summertime Maryland and Virginia
tributary and mainstem monitoring data
from 1984-1988 was averaged to obtain
each value. Higher chlorophyll concen-
trations generally occur in tidal fresh
and transition zones with high nutrient
concentrations.
-------
The SAV Story
0 5
Kilometers
1978 1984 1985 1986 1987
From 1984 to 1987, the acreage of
SAV in the Chesapeake Bay has in-
creased 31%, a partial recovery from
previous declines. SAV in the lower
Bay has shown a steady upward
trend—increasing 24% from 1978
through 1987. After a bottoming out in
1984, SAV acreage in the mid-Bay
zone increased to 22,900 acres. A large
percentage of this increase was due to
continued revegetation of the Potomac
River and growing widgeongrass
populations along the Eastern Shore. In
the upper Bay, SAV acreages have re-
mained relatively stable since 1978.
Overall, these recent increases in SAV
are a positive sign of restoration.
Excessive nutrients pouring into the
Bay cause many of the water quality
and living resource problems that
plague the Chesapeake. Under the 1987
Chesapeake Bay Agreement, plans
were made to reduce controllable
nutrient loadings to the Bay by 40%.
The Agreement also commits the state
and EPA to reevaluate the Baywide
Nutrient Reduction Strategy in 1991.
Jurisdictions in the Bay region
estimated their total point and nonpoint
sources of nitrogen and phosphorus
loadings to the Bay as well as that
portion which is controllable. The total
loadings presented here, calculated for
point sources as of 1985 and for non-
point sources in an average rainfall
year, show the relative contribution of
the sources of these two nutrients from
each jurisdiction. (Source: Baywide
Nutrient Reduction Strategy, July 1989).
Nutrients Flowing into the Bay
1 • 1 • 1 —
§83
(jA/sqi jo suoii
sBuipeo
-*E
_c
20 -
D Nonpoint Source Nitrogen
0 Point Source Nitrogen
%
1
i
1
Q Nonpoint Source Phosphorus
Q Point Source Phosphorus
10
00
I
•6 &
tn i-
0>0
C a>
=5 c
ra o
3 =i
•4 J E
W
MD DC VA
10
PA
MD
DC
VA
-------
Bay wide Commercial Fish Harvests from 1929 -1987
160
JO
S
o
§
m
120-
80 •
40 -
0
50
O
Q.
"5
V)
I
S
o>
CO
CO
40 -
JE 30 -
n
O 20 -
10-
2-
1-
10
•o 8H
? 6H
4 -
2-
m
6-
3-
New Maryland
reporting system
(Additional catch
statistics included)
niftcant decline compared to
the harvests of the late 1800s.
Tropical Storm Agnes
strikes the Bay
Outbreak of MSX in
young Maryland oysters
World War II ends
Sport fishing catch almost
Mice the commercial catch.
Shad population declines dramatically
in response to long-term ovemarvesting
and blockages to their migratory path.
1980 ban on shad
fishing in Maryland
Strategy for removing
blockages to fish
migration adopted
Reproduction drops off
Maryland ban
on fishing
First several decades reflect increasing fishing pressure
1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985
1990
Scientists and mangers use commercial
fish harvests as a tool in assessing the
status of fish populations over long
periods of time. Interpretation is com-
plicated by changes in the level of
fishing effort for different species, lack
of sportfishing catch data and periodic
fluctuations that may result from short-
term climatic changes. Commercial
harvest data for five important Bay
species show that all, with the exception
of the blue crab, have declined sub-
stantially over the past few decades.
Earlier in the century, catches fluctuated
11
due to the amount of fishing effort
expended, type of gear used, fish popu-
lation fluctuations and natural climatic
and hydrologic variability. All species
showed a catch increase just after
World War II when watermen returned
to their occupation.
-------
The Bay's Rivers
1989 STATE OF THE BAY
The Bay's rivers—they form the life-
blood of the Chesapeake, supplying
fresh water, nutrients and sediment. In
this chapter, three rivers illustrate the
gamut of problems and solutions facing
Bay tributaries. The Susquehanna,
draining much of the upper Bay basin,
contributes about half the fresh water to
the Bay. The Potomac represents the
success achieveable with concerted and
cooperative efforts. Finally, the Patux-
ent, site of a burgeoning population, is
showing hopeful signs in response to
aggressive management actions.
Draining the Land:
The Susquehanna
The Susquehanna River, draining an
area of 27,500 square miles of New
York, Pennsylvania and Maryland, is a
major contributor of nutrient loads to the
upper Chesapeake Bay. Although some
of the nutrient load in the Susquehanna
and its tributaries results from point
source discharges in the basin, nonpoint
source runoff from agricultural land is
the major contributor of nutrients enter-
ing the Bay from this river. Strategic
management of this river, therefore, is
exceedingly important for the health of
the entire Bay. Carefully planned and
coordinated nutrient control measures
implemented in the Susquehanna basin
will help achieve the nutrient reduction
objectives of the Chesapeake Bay
Program.
Watershed Monitoring
The Susquehanna River Basin
Commission (SRBC), in cooperation
with the U.S. Geological Survey
(USGS), monitors nutrients and sedi-
ment in the Susquehanna River and its
major tributaries (Figure 1). The moni-
toring consists of monthly baseflow and
selected storm samples. Using this data,
managers estimated how many pounds
per acre of total nitrogen and total
phosphorus the rivers transported from
1985 through 1988 (Figure 2).
The amount of nutrients transported
by the rivers varied somewhat from
year to year at each site but showed
consistent differences between sites.
Watersheds upstream of Harrisburg
generally had lower nutrient losses than
watersheds to the south. This difference
is due to the extensive forests and
limited agriculture in the northern
Susquehanna River basin. South of
Harrisburg, watersheds drain more in-
tensely utilized agricultural and urban/
suburban areas, contributing more
nutrients and sediments to the rivers.
The Conestoga watershed most clearly
demonstrates the effects of intensive
land use. The Pennsylvania Department
of Environmental Resources (PaDER)
also conducts routine monitoring
through its Water Quality Network
program. The network includes 69
stations within the Susquehanna River
basin and is coordinated with the SRBC
monitoring effort.
Figure 1
West Branch
Bloomsburg
The Lower
Susquehanna River
and its Tributaries
Pennsylvania
Maryland
Conowingo Dam
MONITORING STATIONS
DAN Susquehanna River at Danville
LEW W. Branch Susquehanna at Lewisburg
JUN Juniata River at Newport
SHE Sherman Creek at Shermans Dale
HAR Susquehanna River at Harrisburg
PAX Paxton Creek near Penbrook
SWA Swatara Creek near Hershey
WCO W. Conewago near Manchester
YOR Codorus Creek near York
PLE Codorus Creek at Pleasureville
CON Conestoga River at Conestoga
Chesapeake Bay
12
-------
Total Nitrogen & Total Phosphorus Yields
Estimated in the Susquehanna River Basin
10 20 30
Total Nitrogen (Ibs/acre/year)
40
0123
Total Phosphorus (Ibs/acre/year)
Figure 2. Total nitrogen and phosphorus yields estimated for the Susquehanna basin.
There is variation between watersheds, most clearly demonstrated by the agricultural
Conestoga watershed. (The map on the preceding page shows the monitoring stations.)
Precipitation
20 Ibs N
Manure/Fertilizer
400 Ibs N
Pre-BMPs
= Monitoring Shed
Surface Runoff
7.8 Ibs N, 4.4 Ibs P
6.3 tons sediment
Groundwater Nitrate -11 mg/l
Stream
Precipitation
20 Ibs N
Manure/Fertilizer
200 Ibs N
1... ^=
Groundwater Nitrate -12 mg/l
After BMPs
Monitoring Shed
Diverted & Surface Runoff
7.1 Ibs N, 4.1 Ibs P
0.8 tons sediment
Site-Specific Monitoring
The Conestoga River watershed
contributes a major portion of the
nutrient load to the Susquehanna River,
delivered relatively close to the head of
the Bay. The Conestoga, therefore, is of
particular concern to Bay nutrient reduc-
tion strategies and is a target of nonpoint
source pollution controls. An in-depth
monitoring program, now in place, will
determine the effectiveness of agricul-
tural best management practices (BMPs)
in this watershed. The monitoring was
initiated as part of the Conestoga
Headwaters Rural Clean Water Program
(RCWP). The RCWP is a U.S.
Department of Agriculture(USDA)
program which helps farmers install a
variety of BMPs within the project area.
The water quality monitoring
portion of the RCWP was a cooperative
effort between the PaDER and the
USGS with substantial assistance from
the USDA and Penn State University.
Two large farm field sites are now moni-
tored for the Chesapeake Bay Program
by USGS for groundwater and surface
runoff. Surface water is studied at a
small watershed site. The strategy at
each site calls for pre-BMP measure-
ments followed by additional monitoring
after the BMPs are in place.
At one site, located on a traditional
Lancaster County dairy farm, the farmer
implemented various BMPs to improve
water quality. The BMPs included
terracing slopes and changing crops to
control runoff. A manure storage facility
alleviated the problem of having to
spread the manure during inclement
weather. In addition, based on the nutri-
ent needs of the crops, the managers
developed a nutrient management plan
which recommended lower application
rates of fertilizer and manure.
Figure 3. Preliminary results of two best
management practices (BMPs)—terracing
and nutrient management—applied to a
dairy farm in Lancaster County. Runoff
was monitored before (1983 to 1984) and
after (1987 to 1988) implementation of the
BMPs. Nitrogen application to the land
was reduced, resulting in less nitrogen
washing from the site as surface runoff.
Sediment runoff decreased much more
dramatically; phosphorus runoff also
decreased. Groundwater nitrogen levels
have increased, possibly from water move-
ment shifting from surface runoff to
groundwater and residual nitrogen stored
in the soil.. Additional responses may
develop after these BMPs have been in
place longer. (AH values are per acre per
year; N = Nitrogen; P = Phosphorus)
13
-------
Monitoring at the field sites has
yielded preliminary results concerning
the complex relationship between land
use and water quality. There may be
trade-offs between BMPs designed to
improve surface water and those
protecting groundwater. Terraces, for
example, reduce sediment and nutrient
loadings to surface runoff but may also
allow more nitrate into the groundwater
in permeable soils which have received
overapplications of nutrients. To
prevent groundwater degradation in
such areas, terraces should be used in
conjunction with nutrient management.
As an alternative, farmers could use
other methods of controlling sediment
losses in combination with nutrient
management.
Using Data for Management
Pennsylvania ultimately uses the
monitoring data to support management
decisions. The data assist in ranking
areas for remediation ensuring that the
managers expend funds on those pro-
jects providing the maximum reduction
in nonpoint loadings. The SRBC/USGS
watershed monitoring has quantified
substantial differences related to land
use patterns and resultant nonpoint
source pollution impacts. Clearly, some
watersheds such as the Conestoga
require more attention than others.
The monitoring data also improve
calibration of the computer model of the
Chesapeake Bay watershed. This model
provides managers with the ability to
project and evaluate water quality
improvements from various nonpoint
source pollution control options. Both
types of monitoring described above
supply the much needed information to
refine and calibrate this model.
Finally, monitoring data collected
over the years will show whether
nonpoint source pollution control in the
watershed has helped improve water
quality in the streams and ultimately in
the Bay itself. This information needs to
be collected at both the site-specific and
watershed levels and at the mouth of the
Susquehanna River where the nutrients
and sediments are finally delivered to
the Bay. The Maryland Department of
the Environment and the USGS
cooperate to measure these loads
entering the Bay and are coordinating
efforts with Pennsylvania to understand
their derivation in the watershed.
Lessons from the Susquehanna
reinforce the concept that the Bay will
be only as healthy as the water coming
into it.
Road to Recovery: The
Upper Potomac
The upper Potomac River is one of
our nation's major success stories in
water quality restoration. Considered
grossly polluted and a national disgrace
in the 1960s, it is now a healthier, more
productive estuary. This dramatic
improvement is the result of aggressive
pollution abatement programs
undertaken by state, local and federal
governments during the 1970s and
1980s.
The Decline of the Nation's River
Concern over the Potomac River's
water quality and living resources grew
over many decades. As its health
worsened, nuisance algal blooms, low
dissolved oxygen (DO), bacterial con-
tamination, disappearance of sub-
merged aquatic vegetation (SAV) and
declines in the fisheries came to plague
the once bountiful river. In 1925, the
Public Health Service declared the
Potomac in Washington D.C. unsafe
for bathing due to sewage pollution.
Nutrient pollution, primarily nitrogen
and phosphorus from wastewater
treatment plants, led to the Potomac's
algal blooms which were clearly visible
as large blue-green surface mats. These
blooms, along with organic matter from
sewage, caused depletion of the water's
DO upon decomposition. Furthermore,
the blooms and excess nutrients have
been implicated in the decline of SAV
which forms important fish habitat. In
1916, the upper Potomac harbored
abundant SAV but a survey revealed
virtually no plants in the river between
Chain Bridge and Quantico, Virginia
by 1978-1981.
The Root of the Problem
Nutrient pollution is a primary
cause of problems throughout the upper
Potomac estuary. It comes from both
point sources, primarily the sewage
treatment facilities serving the
Washington, D.C. metropolitan area,
and from nonpoint sources, such as
rainwater running off agricultural and
urban land. In addition to nutrients,
point sources contribute organic matter
which can rob the river of DO upon
decay (measured as biochemical
oxygen demand—BOD). If not
properly treated, these sources may also
introduce bacteria to the water.
Figure 4
:JPv Washington D.C.
!!TJ5 tChf:.1?
The Upper
Potomac Estuary
cf^^^Swftls
Blue Plains
Wilson Bridge
Quantico
Major Wastewater
Treatment Plant
City or Town
Little Hunting Creek
Lower Potomac
Woodbridge
N
;
0 Miles 5
Wastewater Treatment Plant Flows
Blue Plains - 297 million gallons
per day (mgd)
Alexandria - 40 mgd
Arlington - 29 mgd
Lower Potomac • 34 mgd
Piscataway -18 mgd
tittte Hunting Creek-5 mgd
14
-------
Point source inputs are relatively
constant throughout the year due to the
population's consistent generation of
waste. Because sewage wastes are
collected at centralized facilities, their
treatment is feasible and practical.
Nonpoint source inputs, however, are
greatly variable—high during storms or
wet seasons and minimal during dry
spells. Nonpoint pollution is much
more difficult to control because the
sources enter the river through many
routes and are episodic.
Responding to the Problems
Until recently, sewage treatment
plant discharges were the primary type
of pollution entering the upper
Potomac. The improved treatment of
these wastes, therefore, has been the
primary focus of the Potomac cleanup.
Up to 1938, when the Washington
D.C. Blue Plains wastewater treatment
plant (WWTP) started operation, raw
sewage flowed directly into the
Potomac River. At that time, Blue
Plains was able to process 130 million
gallons of wastewater per day (mgd) to
a primary treatment level—simply a
screening and settling of wastes. This
level of treatment typically reduces nu-
trients by about 20% and BOD by 50%.
Blue Plains applied secondary
waste treatment in 1959 after a
recommendation from the first Potomac
Enforcement Conference which met in
1957. Secondary treatment aerates the
wastewater, using bacteria to break
down the organic matter. This process
reduces BOD considerably more than
primary treatment. The conference met
again in 1969 and recommended a 96%
removal of phosphorus, a 96% reduc-
tion of BOD and an 85% removal of
total nitrogen from Blue Plains effluent,
setting a timetable for achievement of
these goals by late 1977.
The Federal Clean Water Act,
enacted in 1972, set clean water goals
nationwide and increased the federal
government's role in cleaning up the
Potomac. In 1974, the EPA issued
National Pollutant Discharge
Elimination System (NPDES) permits
which implemented the second
Potomac Enforcement Conference
guidelines.
Along with $250 million from state
and local governments, the EPA
contributed $750 million in the 1970s
to improve WWTPs along the Potomac.
Improvements included adding secon-
dary treatment, advanced treatment (the
addition of chemicals to further reduce
nutrient levels) and chlorination to
eliminate bacterial contamination. Both
phosphorus and nitrogen control were
originally called for but only phos-
phorus removal was implemented.
Managers felt that nitrogen removal
was not economically feasible at the
time and hoped that phosphorus remov-
al alone might limit algae growth.
Blue Plains treatment plant was
issued a new NPDES permit in 1979
which did not limit total nitrogen,
thereby omitting denitrification. The
permit did call for a staged reduction in
effluent phosphorus concentrations
from 1.6 mg/1 to 0.22 mg/1 by 1986.
The plant attained a limit of 0.23 mg/1
phosphorus in 1982.
In 1982, the Potomac Eutrophica-
tion Model (PEM), a mathematical
model of water quality, was developed
to help understand the nutrient enrich-
Total Phosphorus
>. 8000 •
CO
5
O)
•* 4000 '
a
i — i
1965 1970 1977 1982 1987
Total Nitrogen
40000
O)
1965 1970 1977 1982 1987
BOD
30000 -
20000 -
10000 -
0
8000
6000 -
4000 -
2000 -
1965 1970 1977 1982 1987
Figure 5a-Sc. Loadings from the major
WWTPs (see Figure 1) discharging into the
upper Potomac. Total phosphorus and
biochemical oxygen demand both show sub-
stantial declines as a result of management
actions in the 1970s. Total nitrogen
remained relatively constant despite the in-
crease in wastewater handled by the plants.
ment dynamics (eutrophication) of the
upper Potomac. In response to model
results and the federal and state
regulating agencies' perception that the
river was not yet restored (there was a
severe algal bloom in 1983), regulators
decided that WWTPs could not expand
without keeping phosphorus levels
stable. To comply, the expansion of
Blue Plains from 309 mgd to 370 mgd
required a limit on total phosphorus of
0.18 mg/1 down from the 0.22 mg/1
allowed at the lower discharge rate of
309 mgd. Implemented in 1987, this
new phosphorus limit superceded the
NPDES permit of 1979.
In another effort to limit phosphorus
entering the Potomac and all Maryland
tributaries, the Maryland legislature
passed a law in 1985 banning phos-
phates in detergent. The Maryland ban
went into effect in 1986. Washington
DC initiated a ban on phosphate deter-
gents in 1986 and Virginia implemented
a statewide ban in 1987.
These management actions are
responsible for significant reductions of
point source pollution entering the
upper Potomac. The reduction in the
total phosphorus load from major
wastewater treatment plants has been
dramatic, dropping from a high of about
10,000 kg/day in 1970 to less than 300
kg/day in 1987 (Figure 5a).
Total nitrogen loads from the
WWTPs have remained relatively
constant since 1970 (Figure 5b).
Although the plants are not specifically
designed for nitrogen removal, secon-
dary and advanced treatment processes
remove some nitrogen along with the
phosphorus. Nitrogen loads have not
increased, therefore, despite the increase
in wastewater handled by the plants.
BOD increased steadily in the upper
Potomac from 1913 until the addition of
secondary treatment at Blue Plains in
the late 1950s when it dropped almost
50%. BOD gradually rose again until
cleanup programs in the 1970s imposed
stringent restrictions on WWTP efflu-
ents. These programs were instrumental
in reducing the BOD by over 85% from
1970 through 1987 (Figure 5c).
The River Comes Back
As pollution entering the Potomac
has come under control, water quality
trends measured at representative
sampling stations in the upper estuary
between Piscataway Creek and Indian
Head showed dramatic improvement
from 1965 through 1988 (Figure 6a-6e).
15
-------
Total phosphorus in the river has
decreased in concert with phosphorus
removal from the WWTPs in the 1970s
(Figure 6a). The decline in this nutrient
coincides more closely with its removal
in the 1970s than in the 1980s, suggest-
ing that the system was more strongly
influenced by point source loadings in
the 1960s and 1970s. Other factors,
such as nonpoint sources, are becoming
more significant in the 1980s. The
water quality monitoring now includes
nonpoint source inputs from the entire
river above Washington.
Total nitrogen in the upper Potomac
has not varied appreciably from 1965
through 1988 (Figure 6b). As stated,
loadings changed minimally over this
time period.
Chlorophyll, a measure of algal
abundance, has been decreasing in the
upper Potomac since the mid-1960s
(Figure 6c). Although the overall trend
is dropping, some blooms have
occurred since the 1960s. Favorable
climatic and hydrologic conditions
likely fostered the more recent blooms
of 1981 and 1983. Despite similar
conditions observed in 1988, no major
algal bloom developed, signifying that
the massive algal blooms of the past
may finally be under control.
Dissolved oxygen (DO) is vital to
most life and is a key measure of an
estuary's health. Nutrient control
programs of the 1970s have improved
DO conditions by reducing blooms
which eventually decay and consume
large quantities of oxygen. The reduc-
tion of organic wastes in effluent has
also reduced the amount of oxygen
needed for its decomposition once it
enters the river. Since the mid-1970s
DO has increased in the upper
Potomac, indicating the improving
health of the system (Figure 6d).
Water clarity determines the
amount of light available for the growth
Acreage of SAV
Water Quality in the Upper Potomac Estuary
Average Total Phosphorus
Surface Chlorophyll
0.4-
<= °'3-
* 0.2-
0.1-
a
. . .13
100
80 -
60
40-
20 -
0
6549 70-74 75-79 6044 8548
Average Total Nitrogen
6549 70-74 75-79 8044 85-88
Bottom Dissolved Oxygen
3-
1-
65-69 70-74 75-79 8044 8548
Years
Figures 6a-6e. Since 1965, the upper
Potomac has shown substantial water
quality improvements in response to
reductions of loadings from wastewater
treatment plants (Blue Plains, in
particular). The improvements are
characterized by increased water clarity
(greater secchi depth), lower levels of
surface water chlorophyll, lower
concentrations of total phosphorus, and
greater levels of dissolved oxygen in the
bottom waters. Total nitrogen has
remained relatively constant.
6549 70-74 75-79 8044 8548
Secchi Depth
0.8-
« 0.6-
3!
3E 0.4-
02 *
^ "\ '
/ /
\ \
f f
f f S
S X
s,\
e
\ X V
s /
6549 70-74 75-79 8044 8548
Years
1981 1982 1983 1984 1985 1986 1987 1988
Figure 7. SAV showed a formidable recov-
ery from the all-tune lows of the early
1980s. Scientists attribute its reemergence
to improved water quality.
and survival of SAV. An abundance of
suspended matter can destroy SAV and
bottom organisms by settling and
covering them, denying them light and
oxygen. Clarity has shown a steady
increase (Figure 6e), enabling light to
penetrate to greater depths and making
conditions more favorable for the
resurgence of SAV.
Degradation of the Potomac's water
quality was directly responsible for the
sharp decline of SAV. After being
almost nonexistent for nearly 20 years,
SAV returned to the upper Potomac in
1982. The U.S. Geological Survey and
baywide aircraft surveys estimated that
SAV areal coverage has increased from
400 acres in 1983 to over 3600 acres in
1985 (Figure 7). The reemergence of
the SAV can be attributed to several
water quality improvements including
nutrient reduction, lower chlorophyll
and better water clarity.
Some fish species also appear to be
responding to improving habitat
conditions. Largemouth bass fishing in
the upper Potomac was almost nonexis-
tent 10 years ago because degraded
water quality and lack of SAV in the
upper Potomac provided poor habitat.
Today the recreational bass fishery is
booming. The reemergence of SAV was
crucial to the fishery's recovery.
The abundance of waterfowl and
diversity of waterfowl species have also
increased in the upper Potomac. Both
the U.S. Geological Survey and the
National Park Service reported a
significant increase in waterfowl
numbers in the SAV beds. Hydrilla, an
introduced species accounting for much
of the SAV resurgence, is a preferred
food for numerous species of water-
fowl, supplementing the less abundant
native SAV species. Other waterfowl
that do not graze on SAV are probably
feeding on the supply of fish and
invertebrates inhabiting the SAV beds.
16
-------
Recreational activities along the
upper Potomac increased during the
mid-1970s as the river once again be-
came an attraction for people— instead
of a "national disgrace." In 1978, the
District of Columbia organized the first
annual Potomac River Raft Race and in
1981 held the first annual Potomac
River Festival. The surge in recreational
boating and sport fishing has continued
throughout the 1980s.
Dramatic reductions in point source
pollution have produced steady im-
provements throughout the upper
estuary. Although we have come a long
way, additional challenges remain.
More information on fishery
improvements is required to ensure that
the system has returned to a healthy
state. Conditions in the lower estuary
should be closely monitored for
response to improving health and
productivity upriver. Most importantly,
nonpoint source pollution will have to
be controlled as it becomes the
dominant source of pollution entering
the estuary.
/'
i fi
The Patuxent River, a major Chesa-
peake Bay tributary, has experienced
disturbing declines in water quality in
recent years. Rapid population growth
within the watershed has resulted in
major land use changes and increasing
demands on its municipal wastewater
treatment facilities. As the population
surged from 134,000 in the 1960s to
348,000 by 1980, WWTP flows
increased significantly, from 3 mgd in
1963 to 36 mgd in 1980. Land develop-
ment climbed, particularly in the upper
watershed, with a 4% loss of
agricultural land.
Increasing population and urbaniza-
tion of the watershed have increased
nutrient loads to the Patuxent from both
point and nonpoint sources (Figure 9).
Water quality has responded with high-
er peak algal concentrations and criti-
cally low levels of summertime DO in
the lower estuarine reaches (Figure 10).
Figure 8
The Patuxent
River Estuary
Rte. 50 Bridge
• Wastewater
Treatment Plant
N
Broomes Island
/ w*"*
Drum Point
5 10
miles
Maryland's Action Plan In the
Patuxent River Basin
(January 1982)
• Reduce total phosphorus (TP) and
total nitrogen (TN) loadings from
point sources to 191 kg/day and
1832 kg/day, respectively.
• Reduce nitrogen from nonpoint
sources by 907 kg/day.
• Initiate a coordinated monitoring,
modeling and research program to
reduce uncertainty and confirm
system response.
Management Actions
Federal, state, local and academic
officials convened in December 1981 to
formulate a strategy aimed at reversing
the trend of water quality degradation.
The participants used the best available
scientific information, including the
results of a short-term, intensive moni-
toring program and a steady-state water
quality model, to identify the causes of
water quality decline.
As a result of the meeting, Maryland
developed and adopted the Patuxent
Nutrient Control Strategy (January
1982) which outlined specific nitrogen
and phosphorus reduction goals for
point and nonpoint source pollution.
The agreement also called for a
coordinated monitoring, modeling, and
research program to reduce scientific
uncertainty and track the response of
the Patuxent to management actions.
Making Headway
Maryland has made considerable
progress in implementing the goals of
the Patuxent Strategy. The state
initiated a program of phosphorus
removal from point source discharges
in 1982, followed by a statewide ban on
phosphate detergents in December
1985. These actions have dramatically
lowered WWTP inputs of phosphorus
(Figure 9). Nitrogen removal facilities
are under construction at the Western
Branch sewage treatment plant and
should be completed in 1990. Upgrad-
ing the Western Branch facility is the
state's major step towards meeting the
point source nitrogen removal goals.
As recommended by the strategy,
Maryland established a comprehensive
Patuxent Estuary Monitoring, Modeling
17
-------
The Patuxent Through Time
• Total Nitrogen
E3 Total Phosphorus
— Flow(mgd)
| Population
•30 e-
1965
1970
1975
1980
1985
1990
Figure 9. Historical declines of water quality in the Patuxent estuary were accompanied by trends of increasing population, waste-
water treatment plant flows and point source nutrient loads. Recent management actions have greatly reduced phosphorus loadings.
and Research Program in 1983. In-
tended to expand understanding of water
quality problems, the program provides
periodic assessment of improvements,
and if necessary, guides modification of
the Patuxent Strategy's nutrient reduc-
tion goals. The results of the monitoring
program will provide evidence of
advancements in water quality due to
imposed nutrient controls.
System Response to Nutrient Control
To date, phosphorus has been more
stringently controlled than nitrogen and
shows a larger decrease in water
column concentrations. Total phos-
phorus at the head of tide (Figure 11)
and in the upper estuary has dropped
about 30 to 40% since 1983. Nitrogen,
however, shows little more than natural
variability over the same period.
Although the results of phosphorus
reductions are clearly visible in the
upper estuary, the lower areas do not
yet show similar recovery. Since the
upper basin contains most of the major
WWTPs, with only one major WWTP
(Western Branch) discharging directly
to tidal waters, nutrient controls will
have the greatest initial impact on the
upper basin water quality. The effect of
Progress to Date:
The current point source loading of 140
kg/day is below the established goal of
191 kg/day. This phosphorus load is
achieved by requiring all WWTPs with
flows greater than 0.5 mgd to meet a 1
mg/l phosphorus effluent concentration.
Future Plans:
Completion of nitrogen removal facili-
ties at the Western Branch sewage
treatment plant in 1990 will bring point
source nitrogen toads to 1773 kg/day,
less than the goal of 1832 kg/day.
Anticipated Needs:
Sewage flows are projected to reach
64.5 mgd by the year 2000. In order to
maintain the current nutrient removal
goals, some plants will need to remove
phosphorus to a level of 0.3 mg/l, and
all plants will need to incorporate
nitrogen removal practices.
Minimum Levels of Dissolved Oxygen Along
the Axis of the Patuxent Estuary
6.0
£-4.0 H
I2.0
0.0
1936-40
1977-79
Figure 10. Declines in
water quality are
exemplified by the more
extensive region subject to
summer depressions of
dissolved oxygen during
1977 to 1979 compared to
1936 to 1940.
Drum St. Leonard Jack Bay Benedict Lower
Point Creek Marlboro
Phosphorus in the Patuxent
0.4
0)
F 0.3H
£ 0.2 -\
I
0.1
Figure 11. Phosphorus
concentrations at the
Route 50 bridge have
shown significant
decline since the 1981
Patuxent Agreement,
in response to decreas-
ing loads to the
estuary.
1983
1964
1985
1986
1987
1988
18
-------
upriver nutrient removal is less
pronounced downstream due to the
distance'from the point sources, the
influence of the Bay and sediment
nutrient releases.
Projected Water Quality Response
Maryland used monitoring data from
1983 to 1986 in the development of a
water quality model to assess future
benefits of the Patuxent Strategy. The
model predicts significant water quality
improvements should occur throughout
the estuary if all controls recommended
by the strategy are implemented. In
addition to reduced nutrient levels in the
water, the model predicts decreased
chlorophyll and increased DO.
Around Nottingham, the region of
highest chlorophyll levels, the model
projected a decrease in peak concen-
trations from approximately 70 \igfl in
1983 to 50 ng/1 with all nutrient
controls in place. During the summer,
the biomass of algae throughout the
estuary should decrease by about 25%
with nutrient controls. Of the 25%
reduction, the model attributed 18% to
phosphorus control strategies with an
additional 7% occurring with both
phosphorus and nitrogen controls.
The projected reduction in algal
biomass would also reduce the amount
of oxygen-consuming organic matter
settling and decaying on the bottom.
With the nutrient controls of the
strategy and the resultant reduction in
biomass, the model projected that DO
would increase by approximately 0.6
mg/1 in the bottom waters around
Broomes Island, the most severely
depressed region of the estuary. This
19
increase would maintain DO levels over
1 mg/1 throughout the estuary for most
of the critical summer period.
Future Strategies
The goal for phosphorus removal, as
stated in the Patuxent Nutrient Control
Strategy, has been met. When nitrogen
removal at Western Branch becomes
operative, the goals of the strategy for
nitrogen removal will be met as well.
However, management of nutrient
discharges will not end. If the Patuxent
watershed continues to experience
growth similar to past years, sewage
flows will increase. Nitrogen and
phosphorus effluent concentrations
must be reduced further to maintain the
goals of the strategy and to accomplish
the desired improvement of water
quality in the Patuxent estuary.
-------
Managing Living Resources
1989 STATE OF THE BAY
Bringing Back the
Striped Bass
Not long ago, the striped bass or
rockfish was the most popular commer-
cial and sport fish in the Chesapeake
Bay. Throughout the 1960s and early
1970s, commercial harvests of striped
bass increased to record high levels. By
the late 1970s, striped bass landings had
begun an unprecedented decline. In re-
sponse to the decline, this fish became
the focus of increased monitoring and
management in the Bay. Concern about
the striped bass has also extended to the
eastern seaboard states due to the fish's
long migrations— ranging from North
Carolina to Canada— and the extensive
harvesting along this route. Scientists
estimate, in some years, up to 90% of
the east coast landings are from the
Chesapeake Bay stock. The Bay,
therefore, is a major focus of Atlantic
coast management efforts.
Monitoring of Striped Bass
Scientists have monitored Chesa-
peake Bay striped bass stocks since the
late 1800s. The earliest monitoring data
were catch records collected primarily
for economic purposes although catch
data have also been used as a relative
indicator of stock size.
Although catch statistics have been
collected continuously for decades,
they do not provide reliable informa-
tion on the size of the stock or the
causes of striped bass decline. Powerful
economic, managerial, and technologi-
cal forces influence the intensity of
fishing and can bias the catch statistics
relative to the actual number of fish in
the population. Long-term monitoring
programs, independent of commercial
and recreational interests, allow
scientists to track the status and trends
of a fish population and evaluate the
effects of fishing and environmental
factors.
Striped Bass
Life Cycle
The Striped Bass Glossary
Larva: The immature form of an animal
that is fundamentally different from its
parent and must undergo metamor-
phosis before assuming adult
characteristics.
Year-class: All of the fish bom in a
given year.
Juvenile: A striped bass younger than
1 year.
Recruitment: Those juvenile striped
bass which survive to become adults.
Seine Survey: An annual assessment
conducted by Virginia and Maryland to
calculate the juvenile index. Large
seine nets with floats and sinkers are
drawn ashore, capturing a representa-
tive sample of the fish population.
Figure 1: The life cycle of the striped bass including the approximate duration of life
stages and major sources of mortality at each stage in the fish's life.
In addition to determining the
number of fish, monitoring programs
often collect other valuable information
such as sex, size and the number of
eggs carried before spawning. Tagging
fish has also proved useful in tracking
bass migration patterns and estimating
mortality. Striped bass are targeted for
more comprehensive monitoring than
any other Bay species.
Recruitment
One critical type of monitoring for
the fishery determines the success of
reproduction and subsequent recruit-
ment into the adult population. This
type of monitoring can help forecast the
size of the population and evaluate the
effects of habitat or water quality
deterioration at the spawning sites. The
oldest monitoring program of this type
for striped bass is the beach seine sur-
vey. Scientists have used beach seines
consistently since 1954 in Maryland
and since 1967 in Virginia (excluding
1974-1979) to measure the abundance
of each year's young striped bass.
Conducted in striped bass nursery
areas during the summer, the survey
counts juveniles that have grown to
about 2 inches since hatching in the
spring. Once at this juvenile stage,
20
-------
One of the most widely recognized
indices of finfish recruitment, the
juvenile striped bass index, has been
used for over 35 years as a predictor
of both striped bass commercial
harvests and Chesapeake Bay stock
size. Using seine nets, scientists
sample major spawning and nursery
areas to assess the abundance of
each year's class of young striped
bass. The index is merely the average
number of juvenile fish caught in each
haul of the net. Collected each year
the indices are important aids in
determining population trends for the
striped bass. Managers can then use
this information to establish wise
management strategies.
environmental threats to the survival of
striped bass diminish and the seine
survey is able to accurately reflect the
success of each year's spawn. Mary-
land's familiar "juvenile index" is the
annual average number of juvenile fish
caught during the seining of four major
spawning and nursery areas (the
Choptank, Nanticoke and Potomac
rivers and the head of the Bay). Virginia
surveys generate similar statistics for
the York, Rappahannock and James
rivers (Figure 2).
More recent recruitment monitoring
programs sample in the spring when
mortality is highest and the concern for
water quality impacts is greatest.
During this period, scientists collect
striped bass eggs and larvae with fine
mesh nets in some major spawning
areas to assess the abundance and
survival of the fish during the vulnera-
ble early life stages. These programs
often include simultaneous water
quality sampling to examine the factors
that enhance or reduce survival during
these stages. Scientists have also used
bioassays (toxicity studies) extensively
to measure the survival of striped bass
larvae in their natal waters.
Management Actions
In accordance with the Atlantic
Interstate Fisheries Management Plan,
Maryland implemented a fishing mora-
torium on striped bass for Maryland
waters in 1985. Virginia and the Dis-
trict of Columbia followed suit in 1989.
Other Atlantic Coast states have
imposed minimum and maximum size
limits, gear restrictions, creel limits and
closed seasons. As of June 1989,
Virginia, D.C. and the Potomac River
Fisheries Commission banned all
striped bass fishing for at least one
year. These actions are designed to
ensure that at least 95% of the females
from the 1982 and future year classes
will spawn at least once before joining
the exploitable population. The
stringent management actions have
eliminated the immediate danger to
striped bass stocks from overharvest-
ing. Figure 3 demonstrates the effect of
protecting the recent year classes.
Striped bass from the protected year
classes greatly outnumber those
exposed to heavy fishing pressure.
In recent years, traditional striped
bass spawning areas in Maryland have
shown below average spawning suc-
cess. Production of young striped bass
in the Maryland Bay in 1989, however,
is dramatically improved over the
previous seven years. In recent years,
juvenile indices have been at record
highs in Virginia Bay waters.
Studies in the Choptank River have
shown that poor water quality can
increase the mortality of larval striped
bass. This effect intensifies at low
stock levels. Poor water quality in the
spawning areas is due to contaminants
carried from the land and atmosphere
by rain. Acid deposition has been
implicated in the acidification of
spawning habitats and the mobilization
of certain contaminants. Concern about
acid rain's effects on striped bass and
The impressive results of fishing for
striped bass at the Chesapeake Fishing
Fair in the mid-1950s.
other fish species was a major reason
behind Maryland's call for national
legislation to reduce acid rain.
The wide annual variations in
juvenile indices are related both to
environmental factors and to the varia-
ble quantity of eggs produced by
mature females. Acceptable environ-
mental conditions and sufficient egg
deposition should result in increased
numbers of young striped bass in the
Chesapeake Bay.
Historical} uvenile Indices for Striped Bass
o
1950 1955 1960 1965 1970 1975 1980 1985
1990
Figure 2: Maryland's
juvenile index, with the ex-
ception of an average 1982
year class, has remained
near the lowest recorded
levels throughout the 1980s.
This year, 1989, has an
index of 25.2, due to spawn-
ing by the protected 1982
year class. Virginia's index
has increased steadily since
1981, reaching a record high
in 1987. The two indices,
while similar, are not
precisely comparable.
20
1 10 H
§?
Virginia
1965 1970 1975 1980 1985 1990
21
-------
Ages of Female Striped Bass
Upper Bay - Spring 1988
5 Years
4 Years
3 Years
2 Years
7-19 Years
6 Years
Figure 3: In the spring spawning season of
1988, the 6-year olds (1982 year class) con-
stituted the largest portion of the female
striped bass population in the upper Bay.
Managers and scientists designed the
Maryland moratorium and other restric-
tions by Atlantic coast states to protect this
group of females until 95 % had spawned.
To augment the management
actions implemented under the Inter-
state Fisheries Management Plan,
Maryland and the U.S. Fish and Wild-
life Service (USFWS) began a stocking
program in 1985. The purpose of the
program was to supplement the Mary-
land spawning stock of striped bass
using hatchery reared fish. In 1985,
the two agencies stocked more than
370,000 striped bass in the Bay. In
1986, Virginia entered into a similar
agreement with the USFWS and by
1987, the number of stocked fish rose
to 801,341, with most of the increase
coming from Bowden National Fish
Hatchery and two electric utility com-
panies (BG&E and PEPCO). All
stocked fish have received coded wire
tags for use in a tag recovery program.
Signs of Success
During the late 1970s, commercial
and recreational harvests of striped bass
dramatically deteriorated. According to
the Emergency Striped Bass Research
Study produced by USFWS and the
National Marine Fisheries Service in
cooperation with state agencies and
universities, "Reductions in harvest
levels can be attributed principally to a
decline in production of juveniles by
the Chesapeake Bay stock." The
decline in juvenile production can be
attributed to either long-term overfish-
ing, long-term decreased larval survival
rate, or a combination of these two
factors. The availability of reliable
monitoring data was critical in identify-
ing the problem and implementing the
necessary management actions.
Due to these recent management
actions, the striped bass seems to be
maintaining high numbers from each
year class as documented by the
monitoring programs. Striped bass
commercial landings, however, no
longer give even a rough assessment of
stock size since fishing regulations
have been modified to protect the
existing stocks. As a result, long-term
monitoring and tagging studies must
continue to assess accurately the
response of the population to manage-
ment actions and to gauge the health of
the stocks. The 1989 beach seine
survey was sufficiently high in Mary-
land to reach the three-year average
required to permit a highly restricted
commercial and recreational catch of
striped bass in fall 1990. Virginia is
also proposing a restricted season.
We are now about to enter a crucial
period since the majority of the protect-
ed 1982 year class has spawned in the
Chesapeake Bay. By monitoring the
recruitment from this more abundant
year class in conjunction with compre-
hensive water quality monitoring,
scientists can work toward establishing
a link between potential water quality
problems and spawning success. This
new monitoring information is eagerly
awaited and will contribute significant-
ly to continued management success in
restoring the striped bass population.
Plight of the Oyster
Oyster abundance in Chesapeake
Bay is at its lowest level in history. Sci-
entists estimate populations are no
more than 1% of historical levels—
threatening the loss of a valuable
resource and a symbol of the Bay's pro-
ductive fisheries. This continuing de-
cline of the oyster not only symbolizes
the Bay's problems but quite literally
exacerbates the current problems of de-
graded water quality and habitat loss.
The deterioration of the Bay's oyster
population is a complex problem.
Recent outbreaks of parasitic infection,
poor reproduction, reduced survival of
larvae and young oysters, loss of habi-
tat due to sedimentation and anoxia and
commercial overharvesting all have
played a role. At the same time, while
oyster parasites have spread to new
territory resulting in unprecedented in-
fection rates, increases in market price
have spurred greater fishing effort in
areas with surviving oyster stocks.
The loss of oyster populations has
been most severe in regions with
salinities over 12 parts per thousand
(ppt). Only small areas, mostly near the
upstream limits of oyster habitat in the
tributaries, now have parasite-free
oyster stocks. Loss of large harvestable
areas has forced the watermen to
congregate in less afflicted areas. In
Virginia, for example, most watermen
have shifted their harvesting to the
James River beds.
The Deadly Parasites
In 1957, scientists first observed
MSX (Haplosporidium nelsoni), a
lethal parasite of oysters, in Delaware
Bay. Three years later MSX was found
in Chesapeake Bay where it moved
progressively northward. Since then,
changes in freshwater flow and salinity
caused the parasite to disappear, then
reappear, in the Maryland portion of
the Bay. Until the mid-1980s,
distribution of MSX in Virginia
remained stable; three successive years
of drought starting in 1986, however,
Decline of the Oyster in Chesapeake Bay
1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
Figure 4: Harvests of oysters in Maryland have shown a steady decline since the late
1800s. Estimates of the mid 1880s Maryland harvest run upwards of 70 million pounds.
Even back then, the Federal government was concerned that watermen were overfishing
the state's oyster beds. Overall, Virginia harvests have also declined consistently
throughout the same period of time.
22
-------
spurred rapid spread of the parasite in
many areas that had been most produc-
tive during the previous two decades.
"Dermo" is the colloquial name for
the infection caused by another deadly
oyster parasite—Perkinsus marinus.
First observed in the Chesapeake Bay
in the late 1940s, Dermo is currently
found in most of the oyster-growing
areas of the Bay. Dermo does not kill
oysters as rapidly as MSX, but the
infections are more persistent. Over the
long-term, it has likely done more
damage to oysters than MSX. In 1988,
much of the oyster mortality caused by
parasites has been attributed to Dermo.
Despite research efforts, key mecha-
nisms in the epidemiology of MSX and
Dermo remain poorly understood.
Consequently, the ability to combat or
avoid parasite mortality is limited.
Scientists know little about how these
parasites infect oysters or what environ-
mental conditions relate to their
pathology. MSX causes high mortality
rates in oysters only in more saline
waters (> 12 ppt), but year-to-year
fluctuations in MSX occurrence and
virulence remain a mystery. Even less
is known about Dermo; this parasite
seems to infect oysters at all salinities
and is more chronic than MSX.
Recruitment into the Ranks
Each fall, scientists measure the
recruitment or yearly production of
young oysters to the population by
counting the number of spat per bushel
of shell on natural oyster bars. In
Oyster Spat Indices
300
The uncertain status of the oyster in the
Chesapeake is not new. As early as
1889, Encyclopedia Brittanica contained
a long treatise on the immense value of
this bivalve and the potential for its
destruction through overfishing. 'The
oyster fishery is everywhere, except in
localities where the natural beds are
nearly exhausted, carried on in the most
reckless manner, and in all directions
oyster grounds are becoming
deteriorated, and in some cases have
been entirely destroyed."
This concern was justified. In Maryland
and Virginia, watermen harvested over
115 million pounds of oysters in 1880,
worth almost $7 million. Oystering was
the largest of all fishing industries "yield-
ing products three times as valuable as
those of the cod fishery and six times
those of the whale fishery." Although
oysters came from many coastal states
in the U.S., the Chesapeake Bay
supplied 80% of the total yield.
I
« 2001
Q.
CO
1
•i. 1001
1935
1945
i
1955
2000
X
•8
•1500 c
i
•1000 ™
s»
•500 >
1965
1975
1985
Figure 5. The oyster spat index, the average number of young oysters found on a given
amount of dredged shell, shows a significant natural variability. From the 1930s through
the present, however, the average spat index has declined. Reproductive success must
increase if the oyster population is to rebound.
Virginia, these counts are repeated in
the spring. Averaging the spat counts
over a large group of selected oyster
bars gives a numerical index of the
strength of each year class. Over the
past years, these indices of recruitment
have shown a long-term decline. Deter-
mining whether the spatfall declines are
related primarily to declines in oyster
stocks or to other environmental condi-
tions is a critical research question.
Spatfall has decreased steadily since
1985 and is still concentrated in areas
where the parasite is endemic. The
prospects of spat surviving in these
parasite-ridden areas for 3-5 years,
when they will reach marketable size,
are poor. In areas with good strikes but
poor probability of survival in Virginia,
young oysters are transplanted to lower
salinity zones where parasites cannot
survive or their growth is slowed and
the oysters can reach harvestable size.
Oysters and the Environment
The American oyster is an extreme-
ly hardy animal under most conditions,
thriving over a wide range of salinity,
temperature and geographical area.
Adult oysters are resistant to high
levels of many contaminants, including
heavy metals, and can also survive the
complete absence of dissolved oxygen
for a few days.
Probably the greatest environmental
threat to oysters is sediment. Large
quantities of suspended sediment inter-
fere with normal feeding. When sedi-
ment settles to the bottom, it may
smother oysters if their growth does not
outpace the sedimentation rate. Most
Hand tongers working the oyster beds at the mouth of the Severn River in the mid-1950s.
They are standing on a Dead Rise boat, the standard Bay oyster boat.
23
-------
MSX-Free Oyster Habitat Zones
SUSQUIMANNA
Figure 6. The areas shaded
on the map have average
salinities between 5 and 12
parts per thousand (ppt).
MSX infections cause
oyster mortality only above
12 ppt Oysters generally
do not live in waters
fresher than 5 ppt. Current
, and future management
V will focus on these shaded
areas where the prospects
for oyster survival are
better.
Dermo infections do not
appear to be limited by
salinity. The 12 ppt iso-
halines were drawn from
1985 (average year) moni-
toring data and the 5 ppt
isohalines from average
summer predicted condi-
tions (Corps of Engineers
Low Flow Study, 1982).
important, a fine layer of sediment on
hard cultch (material, such as shell, to
which oysters attach) prevents spat
from attaching. A successful spat set
can be destroyed in the first few days if
covered with a layer of sediment. Sedi-
mentation can be caused by winds and
waves stirring up the bottom, heavy
rainfall with sediment runoff from
cleared land, dredging or other physical
disturbance to the bottom, shoreline
erosion and decaying algal blooms.
Scientists think that dissolved
oxygen depletion (hypoxia) may have
destroyed oyster bars in some parts of
the Bay and its tributaries. Oyster bars
tend to occur along the upper flanks of
deep channel areas. Hypoxia develops
seasonally in deep waters when the Bay
is stratified (cool, salty water at depth
and warmer, fresher water near the
surface); under certain conditions, this
deep hypoxic water can move into the
shallower waters. If hypoxia is suffi-
ciently severe and persists long enough
over the beds, adult oysters and the as-
sociated community may die. Hypoxia
also may prevent larval settlement and
recruitment to affected oyster bars.
Even without physical intrusion of low
oxygen water, the shallows may occa-
sionally become hypoxic due to local
eutrophication.
Although they are tolerant of some
types of pollutants, oysters have been
threatened in recent years by the use of
tributyltin (TBT) in boat bottom anti-
foulant paints. TBT causes grotesque
shell deformities and is extremely toxic
to oyster larvae. Severe restrictions by
the states on the sale and use of TBT
paints have reduced the potential for
harm, but TBT and related compounds
are still found in the environment and
oyster tissue (see section on TBT).
Oysters and the Ecosystem
When abundant, as they once were
in the Bay, oysters play at least two
dominant ecological roles. First, large
populations of these bivalves filter im-
mense quantities of water. Scientists es-
timate that prior to heavy exploitation
by man, oysters filtered the entire vol-
ume of the Bay in only a few days.
Much of the suspended matter was
removed by oyster filtration, greatly
24
reducing algal concentrations. The
increased light penetration, curtailment
of the plankton population and high
rates of dissolved and paniculate waste
production by oysters likely had pro-
found effects on the ecosystem. The
paniculate wastes helped to nourish
bottom-dwelling deposit feeders while
dissolved wastes resupplied nutrients to
the algae. The nature of these effects on
the whole ecosystem can only be sur-
mised; our remnant oyster population
now requires more than a year to filter
the entire volume of the Bay.
The other important ecological role
for oysters is a by-product of their hard
shells. These shells act as platforms for
many organisms including barnacles,
mussels, anemones, sponges, worms
and tunicates. Like oysters, most of
these animals are filter feeders and their
abundance amplifies the effects of oys-
ter filtration described above. Man has
created substitute habitats for some of
these creatures by building piers, bulk-
heads and revetments. It is unlikely,
however, that manmade structures have
fully replaced either the quantity or
quality of habitat once provided by the
oyster bars.
The Outlook for the Oyster
The states have invested substantial
amounts of money and effort into main-
taining harvestable stocks of oysters
through seed and shell repletion pro-
grams. In the seed programs, juvenile
oysters are collected where they are
abundant but cannot grow well and
move them to areas where they are able
to grow rapidly and are harvestable
after 2-3 years. Under shell repletion
programs, oyster shells dredged from
buried oyster bars or taken from pack-
ing houses are placed on top of natural
oyster bars to maintain the hard
bottoms which favor spat settlement.
Oyster management also entails season-
al closures, gear restrictions, catch
limits and restrictions on the hours of
fishing. Leasing programs permit
individuals to reserve areas of the Bay
bottom for private culture of oysters.
Despite these management efforts,
oyster harvests have continued to
decline. There are no methods presently
available to prevent the loss of stocks
to the parasite. When a severe outbreak
of MSX struck Tangier Sound in 1963,
there were no harvestable oysters for at
least 5 years. It was almost 10 years
before the yield approached economi-
cally attractive levels, yet oyster
-------
densities in this area never returned to
pre-parasite levels.
Scientists hope that a combination
of genetic research and natural
immunity eventually will lead to more
parasite-resistant stocks. Developing
widespread immunity to MSX and
Dermo in the Bay's natural oyster
population, however, is a long-term
prospect. On the positive side, commit-
ments to improve water quality and
environmental management in Bay
watersheds offer the promise of more
and better oyster habitat. The baywide
management plan for oysters, com-
pleted in July 1989, provides an oppor-
tunity for Maryland and Virginia to
plan jointly for the future of the oyster.
Oystering has been a traditional
way of life and a means of support for
many people and communities around
the Bay. Just as important, oysters
were once dominant members of the
Bay ecosystem, providing many other
species with a way of life. Rebuilding
oyster populations will be one of the
toughest challenges in the work to
restore the Chesapeake Bay.
The SAV Link
Submerged aquatic vegetation—a
distinctly sterile name for a set of
plants that shelters a profusion of life.
These plants are key elements in the
restoration and maintenance of the
Bay's health. One of the most alarming
trends, therefore, over the past few
decades has been the decline of the
submerged aquatic vegetation (SAV)
beds that once flourished in the Bay.
The rapid loss of these plants prompted
the scientific community to study the
problem, search for causes and propose
solutions. The scientists discovered that
all species of the aquatic plants were
affected and the loss was occurring
throughout the Chesapeake Bay. More
importantly, the decline was not due to a
single factor but to overall deterioration
of Bay water quality.
Aquatic Grasses
An essential link in the food web,
SAV is a food source for many species
of waterfowl, fish, shellfish and inverte-
brates. The plants provide habitat and
shelter for a variety of Bay species. Fish
utilize the beds as nurseries, receiving
protection from predatory fish. Crusta-
ceans, such as the blue crab, hide among
the grasses during their vulnerable molt.
While providing an invaluable
source of food and cover for many Bay
species, SAV also maintains the
integrity of the surrounding shallow
water habitat. SAV photosynthesis helps
to oxygenate Bay water. The plant
leaves baffle water currents, allowing
suspended sediment particles to settle
out of the water. The root systems bind
the substrate and reduce sediment
resuspension while large, dense beds
dampen wave energy and slow shoreline
erosion. Most significantly, in a system
plagued with excess nutrients from
urban, suburban, and agricultural
sources, the ability of SAV to take up
nutrients during the spring and summer
Sunlight attenuated by suspended
sediment and phytoplankton in the water
Resuspcnded
bottom sediment
from wave action
With rapid development around the
Bay and increased use of the Bay, SAV
not only decreased drastically in
abundance but also changed in species
composition. The species shifts have
important implications for the animals
inhabiting the Bay. In some cases,
non-native species such as Hydrilla or
water chestnut may take over a portion
of the Bay or tributary, reducing the
local diversity of plants. As diversity
drops, the diversity of animals that can
live in the SAV habitat also declines.
Waterfowl, in particular, are highly
dependent on certain types of SAV for
their food supply.
Susquehanna Flats is an area which
suffered serious declines and species
changes—then was repoputeted by
some native species. In the late 1950s
and early '60s, many native grasses
suffered while the introduced Eurasian
watermilfoil spread. Although some
native species recovered during the
1960s, almost all the SAV disappeared
in the 70s. By the mid-1980s, SAV
returned with the resurgence of wild
celery and other native species. The
return of these grasses bodes welt, for
along with the SAV will undoubtedly
come a variety of other animal and
plant life.
Figure 7. Bay scientists have linked reduced light availability to the baywide decline of
the SAV beds. Reduced sunlight penetration, due to excessive phytoplankton and
suspended sediment, results in less available light energy needed for photosynthesis.
25
helps to retard eutrophication of the
Bay waters.
Since these plants play an integral
role in the healthy functioning of the
Bay, researchers have monitored the
dwindling of SAV since 1971. Annual
ground surveys by the Maryland
Department of Natural Resources at
over 600 sites showed a steady decline
of SAV in Maryland waters. The
percentage of vegetated sites decreased
continuously from 28.5% in 1971 to a
mere 12.3% in 1977.
In 1978, researchers conducted the
first baywide survey of SAV using
aerial photography. The photographs
revealed that SAV covered 41,110
acres of Chesapeake Bay bottom. By
1984, this figure had dropped to 38,053
acres although by 1987 it had increased
to 49,714 acres. Although the slight
increase is encouraging, the current
population does not approach the
100,000 to 300,000 acres estimated for
the mid-1960s.
The Cause of SAV Decline
In the late 1970s and early 80s, re-
searchers at the University of Maryland
and the Virginia Institute of Marine
-------
Science (VIMS) began to unravel the
reasons behind the grasses' decline.
They focused on those environmental
factors affecting plant growth, includ-
ing processes such as eutrophication
and sedimentation which decrease light
penetration into the water (Figure 7).
They also studied the effects of toxi-
cants, especially herbicides, to which
the SAV may have been exposed.
When nutrient (phosphorus and
nitrogen) concentrations are too high,
phytoplankton bloom in the water and
epiphytes (plants which live on the sur-
face of other plants) grow on the SAV.
The phytoplankton cloud the water,
diminishing light reaching the grasses.
The epiphytes further lessen available
light. These stresses reduce the depth at
which SAV can live, restricting growth
to shallow water where increased wave
energy, erosion and grazing by water-
fowl further stress the plants. In some
cases, the stress becomes overwhelm-
ing and the grasses are completely lost.
As sediment washes into the Bay, it
also restricts light penetration. Al-
though some silt and clay is needed to
create a suitable substrate for the plants
to root, excessive particulates in the
water significantly lessen water clarity.
Poor agricultural practices and acceler-
ated land development have introduced
a sediment overload. Runoff carries this
sediment into the water, where the
particulates may remain suspended
long enough to reduce sunlight
reaching the plants.
Researchers also examined agricul-
tural herbicides, such as atrazine and
linuron, for their effects on SAV
growth. At high concentrations, 50-100
parts per billion (ppb), atrazine severely
reduces photosynthesis by SAV and
complete recovery may not be possible.
Five to 10 ppb produced a 10-20% loss
of photosynthesis. Surveys since 1977
have not found concentrations over 20
ppb; even with concentrations of 10-20
ppb, however, the plants took 1-4
weeks after the initial exposure to fully
recover. If the interval between
exposures is shorter than the plants'
recovery time, then photosynthetic im-
pairment may persist. The researchers
concluded that these herbicides alone
did not cause the SAV decline but, in
combination with other environmental
stresses, certainly contributed.
Monitoring SAV Habitat
In the 1980s, the search for the
reasons behind SAV loss moved from
the laboratory into the field. To verify
the links among excessive nutrients,
suspended sediment and diminished
light, and to evaluate the impact of
other physical factors (such as wave
action) affecting SAV growth,
researchers set up nearshore habitat
monitoring programs.
Scientists at Harford Community
College began to monitor shallow
water habitats on the Susquehanna
Flats and in the surrounding tidal
tributaries in 1985. The vast beds of
SAV that once covered the
Susquehanna Flats, prime habitat for
migratory waterfowl, all but disap-
peared in the late 1960s and early
1970s. Water quality monitoring in
vegetated and unvegetated areas of the
upper Bay was combined with SAV
transplanting to define the habitat
requirements of tidal-fresh SAV
species. After more than three years of
monitoring, the relationship among
SAV, nutrients, sediments and light
levels is emerging.
Key questions concerning the
occurrence of high nitrogen concentra-
tions with low phosphorus levels and
the impact these have on SAV in tidal
fresh areas are being addressed as part
of a baywide analysis of all SAV
habitat monitoring data within the next
year. Habitat monitoring data from the
upper Bay and the Potomac River will
be instrumental in answering these
remaining nutrient limitation questions.
In the Potomac River, the U.S.
Geological Survey has monitored water
quality status and trends since 1978
when SAV was completely absent in
Figure 8
SAV in the Choptank
Little Choptank River
SAV Abundance1
Chlorophyll a (u,g/l)2
Dissolved Inorganic
Nitrogen (mg/l)
Dissolved Inorganic
Phosphorus (mg/l)
Light Attenuation (rrr1)
Secchi Depth (m)
Transplant Success
Total Suspended
Solids (mg/l)
Resurgence of SAV
2.4-10
0.04-010
0 002 - 0 007
0.8 -1 2
1.4-2.1
Good
30-13.0
Marginal SAV
3.0-150
003-0.14
0.003 - 0.008
1.0-1.9
0.9-1.7
Temporary
6.1-22.0
SAV Absent
4.0 - 29.0
0.02 - 0.36
0.01 - 0.05
1 7-5.0
03-1.0
None
9.2-32.0
1 Primarily widgeongrass (Ruppia mantima)
2 Ranges of annual growing season (April - Sept) medians for surface samples from nearshore stations in each section (1986-1988)
26
-------
Figure 9
SAV in the York
SAV Abundance1
Chlorophyll a (u,g/l)2
Dissolved Inorganic
Nitrogen (mg/l) 021 - 25 028- 15
Dissolved Inorganic
Phosphorus (mg/l) 023-050 015-040
Light Attenuation (m-1) 1.35-219 132-140
Secchi Depth (m) 08-13 1.2-13
Transplant Success None Temporary
Total Suspended
Solids (mg/l) 97-223 104-192
1 Primarily eelgrass (Zosfera manna], some widgeongrass (ffupp/a mantima]
2 Ranges o! annual growing season (spring and autumn) medians lor surface sample from neaishore stations in each section (1985-
1988), only one station (Mumlort Island) in 'marginal zone' before 1988
Resurgence of SAV
21 -10.7
.022- 11
010- 027
0 73 -1 23
14-23
Good
47-135
the upper Potomac. The USGS contin-
ued monitoring through 1988 when
vegetation extended from the District of
Columbia south to Quantico, Virginia.
The USGS is analyzing this 10-year
data set, which captured the "before,
during and after" water quality condi-
tions associated with the reestablish-
ment of SAV in the Potomac, to develop
habitat quality requirements.
Researchers at the University of
Maryland's Horn Point Environmental
Laboratory initiated a similar program
in the Choptank River. The 4-year water
quality monitoring program has
documented habitat quality patterns
within the Choptank's nearshore envi-
ronments (Figure 8). In the lower river,
decreased nitrogen and phosphorus
levels coincided with healthy SAV beds,
survival of the transplanted SAV and
successful natural revegetation. In the
less saline water, diminished water
quality reduced SAV distribution and
abundance; transplanting success was
marginal. In the oligohaline (0.5-5 ppt)
and tidal fresh reaches of the river, high
nutrient and chlorophyll a concen-
trations and reduced light levels were
matched by the absence of SAV beds
and the failure of all transplants.
Scientists at VIMS began detailed
investigations of the relationships
between environmental quality and the
growth of the two primary SAV species
in the lower Chesapeake Bay—eelgrass
and widgeongrass— starting in the
1970s. A biweekly sampling program,
initiated in 1985, focused on the
shallow water habitats of the York
River to monitor environmental quality
along an upriver gradient: from the
lower river which currently and
historically supported viable SAV beds
to the upper reaches devoid of SAV
(Figure 9).
27
The unvegetated upriver stations had
consistently high nutrient concentrations
and turbidity levels. A downriver
gradient of improved water quality
matched increasingly abundant SAV
beds in the shoal waters of the York
River. Survival of transplanted eelgrass,
planted each fall to determine the
potential for SAV growth, production
and survival at the sites, closely coincid-
ed with the water quality gradient.
Results from the York River SAV
habitat monitoring program are provid-
ing insights into the habitat quality
requirements of the Bay's SAV species
which live in high salinity areas. The
response of the plants in these areas has
been different from low salinity species
in terms of their relative tolerance of ni-
trogen and phosphorus concentrations.
The habitat quality requirements being
developed for these lower Bay species
should be transferable to other high
salinity areas of the Bay where the same
species were present historically.
Habitat Requirements
Current research programs focus on
the distribution and abundance of SAV,
assessment of transplanting methods and
intensive water quality monitoring of
nearshore habitats. These programs are
providing quantitative habitat quality
requirements for various SAV species.
The Bay Program published an initial
list of SAV habitat requirements for
high salinity zones in the "Habitat Re-
quirements for Chesapeake Bay Living
Resources."
A set of requirements for the tidal
fresh and oligohaline salinity zones is
not yet established. Researchers are now
developing the requirements for these
zones. Once determined, programs can
address habitat problems in those
watersheds exceeding established
requirements. In addition, regional
restoration goals can be set for SAV
acreage, abundance and species
diversity considering historical
abundance, distribution records and
potential habitat.
The growth and survival of SAV is
intricately tied to the water quality of the
Chesapeake Bay, making it a valuable
indicator of an area's ability to support
living resources. Attempts to improve
Bay water quality can be evaluated by
monitoring the response of SAV to
modifications of habitat quality.
Changes in SAV distribution and
abundance ultimately serve as a measure
of baywide restoration.
-------
T
oxicant Case Studies
1989 STATE OF THE BAY
The TBTProblem
Within the past two years, tributyltin has
become part of the vocabulary of many
boat owners, marina operators, scientists
and government agency personnel.
Tributyltin or TBT provides an
important case study where the Chesa-
peake Bay Program's monitoring efforts
directly influenced state and national
TBT legislative and regulatory
decisions. TBT is the first example in
which the government restricted use of a
pesticide based solely on the risk to the
environment—not human health.
Tributyltin was most commonly used
as an additive to boat bottom paint,
preventing the undesirable growth of
barnacles, tubeworms and other fouling
organisms. Industry also used TBT as a
stabilizer in the production of PVC
pipes, paper and textile fungicides,
industrial cooling water biocides,
household disinfectants, agricultural
pesticide products and as a catalyst in
many other chemical processes.
Approximately 624,000 gallons of
antifouling paint, containing an
estimated 1 million pounds of TBT
compounds, were sold annually
nationwide. The major use of TBT paint
was for ships and boat hulls with less
than 4% used on docks, buoys, crab pots
and fish nets. In the Bay, leaching of
TBT from boat bottoms posed the
greatest potential threat given the direct
exposure of vulnerable organisms to the
pesticide.
By 1985, scientists began to report
lethal and chronic effects of TBT
exposure at concentrations in the low
parts per trillion (pptr). Finfish larvae
were found to be sensitive at parts per
billion (ppb) levels of TBT. Scientists
documented unnatural shifts from female
to male gender in one species of snail
exposed to less than 20 pptr. At the same
time, managers undertook efforts to
assess the need for restrictions in the use
of TBT as a boat bottom antifoulant.
In January 1986, the Environmental
Protection Agency initiated a special
review of TBT used as an additive to
antifouling boat bottom paints.
Maryland and Virginia had already
begun efforts to monitor TBT levels in
the Bay. Given the Chesapeake Bay
Program's interest in the issue and a
TBT Timeline
Early 1980s — Scientists begin to
actively test the toxicity of TBT;
first reports of visible impacts of
TBT on adult oysters in Europe.
May 1985 — Navy supports
intensive survey of Back Creek.
September 1986 — EPA com-
pletes intensive survey of four
northern Bay harbors.
July 1987 — Governor Schaefer
signs Maryland's TBT legislation
into law.
June 1988 — Virginia adopts TBT
water quality standard effective
September 1988.
June 1988 — President Reagan
signs into law the "Organotin
Antifouling Paint Control Act
of 1988."
June 1989 — EPA publishes
draft water quality criteria for TBT.
1989 — Maryland to adopt TBT
water quality standard.
1989-1990 —EPA to receive
additional data from 1986 Data
Call-In from manufacturers.
growing data base on TBT
concentrations throughout the
Chesapeake Bay, EPA
undertook an intensive survey
of several Bay harbors. The
EPA's Chesapeake Bay Liaison
Office convened a TBT workgroup
to assist in the survey design and to
coordinate Bay monitoring and
research in support of the TBT legis-
lative and regulatory decisions under
consideration at the state and national
levels. Representatives from Maryland
and Virginia state agencies, research
scientists from the Virginia Institute of
Marine Science(VIMS) and Johns
Hopkins University, the Navy and EPA
composed the workgroup.
28
Early 1960s — TBT first regis-
tered and used as an additive to
antifouling boat bottom paint.
Mid 1980s — Scientists report
measurable effects of TBT at the
low parts per trillion level.
July 1985 — Maryland initiates
one-year TBT suryeyprogram;
EPA initiates special TBT re view.
March 1987 — Goverror Baliles
signs Virginia's TBT legislation
into law.
October 1987 — EPA publishes
preliminary determination to cancel
certain TBT registrations and
reclassify TBT antifouling paints
as restricted use pesticides.
September 1988 — EPA publishes
regulations cancelling/restricting
continued registration and use of
TBT products used as boat
bottom antifoulants.
1989-1998-National TBT
monitoring program.
June 1993 — EPA to report
to Congress on effectiveness
of existing laws.
Monitoring Program
Response
Maryland funded Johns
Hopkins University (JHU) to
monitor TBT concentrations
monthly at 8 stations located in the
northern Chesapeake Bay for one
year (July 1985-June 1986). With
continued support from the Navy and
Maryland, JHU scientists initiated an
intensive boating season survey of
Back Creek, Annapolis, Maryland in
1986, resampling in 1988 and 1989.
Virginia supported efforts by VIMS to
begin a long-term TBT monitoring
program on Sarah Creek (tributary to
the York) and Hampton River (tribu-
-------
tary to the James). The program, initiat-
ed in January 1986, includes monthly
sampling of 8 stations. The Navy also
conducted its own limited sampling of
the Norfolk/ Elizabeth River harbor
area in 1984. EPA funded and carried
out an intensive survey of TBT levels
in 4 harbors (Spa Creek, Solomons
Harbor, Oxford Harbor and Plain-
dealing Creek) located in northern
Chesapeake Bay during the 1986
boating season.
TBT in Chesapeake Bay
Figure 1 summarizes data from the
1984 to 1988 Chesapeake Bay TBT
monitoring and survey programs. It
shows the ranges of TBT concen-
trations from the single or combined
sets of sampling locations versus indi-
cators of toxicity or potential impact
from exposure to TBT. EPA has
posted a chronic water quality criterion
for TBT of 26.4 pptr for freshwater and
10 pptr for saltwater. Respective acute
water quality criterion are 10 and 26.6
pptr. Chronic toxicity causes impair-
ment or abnormalities; acute toxicity is
lethal. The ranges of TBT concentra-
tions and total average concentration
for most of the listed sampling sites are
greater than the EPA chronic water
quality criteria. Concentrations at many
of the sites were high enough to poten-
tially inflict chronic impacts on local
mollusk and plankton communities.
Many of the sites sampled in Mary-
land waters were harbors with busy
boat traffic and marina activities. TBT
The Toxicity of TBT
Snails
Chronic Toxicity
2 - 20 pptr
Oyster
Chronic Toxicity
10-50 pptr
Finfish
Chronic Toxicity
> 200 pptr
Crabs
Acute Toxicity
> 420 pptr
Finfish
Acute Toxicity
> 960 pptr
1000
Snails
Acute Toxicity
> 10 pptr
Crabs
Chronic Toxicity
> 90 pptr
Plankton
Growth Inhibition
100-350 pptr
Oysters
Acute Toxicity
> 900 pptr
2000
pptr = parts per trillion
concentrations at these sites averaged
well above the EPA water quality
criteria for protection against sublethal
effects. At the remaining sites, with
waters less impacted by boating and
marinas (Plaindealing Creek and the
Choptank River), no TBT was detected.
TBT concentrations ranging from
20-24 pptr, however, were measured in
the Potomac River.
The range and average concen-
tration of TBT for individual sites
directly reflect boating activity levels in
the immediate vicinity (Figure 1).
Even within a harbor, there is a
gradient of TBT concentration from
"upstream" areas of concentrated
boating activity towards the adjacent
tidal river, again reflecting the
correlation of boating with TBT
concentration.
Data from other Virginia sites also
correlated with boating and shipping
activity. The range and average of
TBT concentrations for the Hampton
and Elizabeth rivers indicate greater
local TBT sources compared to the
York and James sites where TBT
concentrations averaged less than 10
pptr.
Resultant Management Actions
Based on the findings from the TBT
monitoring programs, research findings
on TBT toxicity to estuarine organisms
and EPA's special review, Maryland
and Virginia passed legislation to
restrict the use of TBT-based
antifouling boat paints. The TBT
Workgroup cooperated with the
Chesapeake Bay Commission to ensure
approval of this legislation. Passage of
the Maryland and Virginia laws
provided a model for resultant
legislation passed by numerous coastal
states and for national legislation
enacted in 1988.
Data from ongoing monitoring in
Chesapeake Bay were submitted to
EPA's Office of Pesticide Programs,
Figure 1. The map
shows all sampling sites
in Chesapeake Bay
where scientists have
measured TBT in the
water since 1984. The
lines show the range of
values measured over
the sampling period
while each dot repre-
sents the average TBT
concentration found at
that site. At the
majority of sites, TBT
levels exceeded the
EPA water quality
criterion. Several
stations showed levels
sufficiently high to
cause abnormalities in
some organisms.
ND=Non Detectable
EPA
Chronic H20 Chronic Effects Growth Inhibition
Quality InMollusks of Plankton
(10-26) (20-100) (>100)
C&D Canal
Baltimore Harbor
Spa Creek
Back Creek
Slevensvllle
Chester
Plaindealing
Oxford
Choptank River
Solomons Island
Potomac River
Sarah Creek
York River
Hampton River
James River
Little Creek
Elizabeth River
ND
ND
ND
39 •
1 60
•24
129
120
-1300
0 20
100
(In parts per trillion)
29
-------
Average TBT Concentrations at Sarah Creek, Virginia
Summer '86
Winter'86
Summer "87
Winter '87
Summer '88
Figure 2. TBT concentrations at Sarah Creek, tributary to the York River, show peaks
which coincide with the late spring and summer boating season. TBT levels drop off
during the winter when most recreational boats are out of the water.
which had responsibility for the special
review of TBT. This data set, the most
complete and extensive for such a large
coastal system, has played a significant
role in EPA's risk/benefit analysis of
TBT. EPA has since published
regulations cancelling or restricting the
use of TBT antifouling paints based in
part on the Chesapeake Bay TBT
monitoring data and research findings.
Effectiveness of Legislation and
Regulations
Congress has requested that EPA
carry out a ten-year national TBT
monitoring program to assess the
effectiveness of the national legislation
in reducing environmental levels of
TBT. Member agencies of the
Chesapeake Bay Program will continue
to coordinate TBT monitoring programs
in a regional effort to evaluate national
and state actions to diminish contami-
nation of the Bay by TBT.
Kepone in the James
The James River, the southernmost
tributary of the Chesapeake, is the third
largest tributary entering the Bay. It
supplies about 16% of the freshwater
flowing into the Chesapeake. The river
originates in West Virginia and drains
approximately one quarter of Virginia.
It boasts a diverse and valuable fishery
with much of the river forming impor-
tant spawning and nursery grounds.
Major shellfish species harvested in the
James River include hard clams, blue
crabs and oysters. Seed oysters, juve-
niles of 1-6 cm in length, are abundantly
harvested from the James and sold to
watermen for planting in oyster-
depleted areas of the Bay. Scientists
estimate that 70% of the annual Virginia
.oyster production is dependent on seed
oyster production in the James.
Kepone Contamination
From 1966 through 1975, Allied
Chemical Company and its subsidiary
Life Science Products, Inc (LSP),
produced a persistent chlorinated
hydrocarbon insecticide called kepone.
During production, the company
discharged kepone into the James River
Estuary at Hopewell, Virginia. They
released an estimated 90,720 kg of
kepone to the environment through
atmospheric emissions, wastewater
discharge and disposal of off-
specification batches. Kepone contami-
nated the river from Hopewell to
Newport News; scientists found fish
adulterated with the substance as far
upriver as Richmond.
In July 1975, the Virginia Depart-
ment of Health (VDH) closed Life
Science Products due to inadequate em-
ployee protection in kepone production.
State and federal governments formed
task forces to evaluate the situation and
recommend action. Due to an overall
lack of knowledge concerning kepone,
they also initiated research efforts.
The EPA modeled the movement of
kepone in the estuary, investigated
means of kepone disposal and fixation
and determined the potential effects of
kepone on marine organisms. At the
same time, VIMS evaluated the impact
of kepone on aquatic animals, its accu-
mulation in sediments and biota and the
uptake and release of the toxicant by
specific animals. The VDH simultane-
ously researched the human health
aspects of the kepone problem.
State and federal agencies initiated
environmental monitoring to determine
the extent and degree'of the kepone
problem. They found widespread
contamination of the water, sediment,
fish, and shellfish. As an extension of
the initial study, the Virginia State
Water Control Board designed and
30
implemented a long-term monitoring
program to evaluate and track the
kepone problem.
Monitoring Kepone
In the Water. Scientists collected and
analyzed James River water samples
from approximately 60 stations for
kepone from 1976 through 1981.
Levels in the water were highest in the
middle reach of the estuary from Jordan
Point to Jamestown Island and de-
creased towards the sea. Concentrations
peaked in the summer. Water sampling
was finally eliminated from the
monitoring program in 1982 due to
continuous non-detectable and trace
levels of kepone.
In the Sediment. As part of the ongoing
monitoring program, scientists collect
core sediment samples throughout the
river and analyze for kepone at differ-
ent depths below the sediment surface.
Sediment monitoring stations are
located throughout the entire contami-
nated reach of the river. From 1976
through 1981, technicians collected
samples at approximately 60 stations.
Stations where kepone was not detect-
ed have been dropped over the years.
From 1982 through the present, 32
stations have been sampled annually.
Kepone accumulates in the sedi-
ment due to its affinity for paniculate
material. It associates with coarse
sediments having high organic content
in the upper and middle river. In the
lower river, it generally associates with
fine-grained sediments. Higher
sedimentation rates in the channel tend
to bury the contaminated sediment
while lower rates in shoal areas allow
contaminated sediment to remain at the
surface.
Kepone levels in sediment also vary
greatly along the river. The Hopewell
area shows high levels of contamina-
tion but this drops below detection
downriver at Newport News. Kepone
contamination is greatest where fresh
and salt water meet; the mixing of
seaward-moving fresh water and salt
water moving upriver traps much of the
contaminated river-borne sediment
load. Kepone levels in James River
sediments have generally decreased
since the onset of the monitoring pro-
gram as a result of the burial and
dilution of kepone-containing sedi-
ments by less contaminated sediments.
In the Finfish. A large data base and
knowledge of the kepone situation has
allowed the fish monitoring program to
be reduced over the years while still
providing the necessary portrait of
kepone levels in James River fish.
Currently, nine target species are
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Kepone, a complex insecticide, is
known to chemists by the bewildering
name of decachloro-octahydro-1,3,4-
meheno-2H-cydobuta[cd]=penatalen-2-
one. Chemically, it is similar to chlordane,
mirex, aldrin, and dieldrin. In the past the
majority of kepone was shipped abroad
to eradicate the Colorado potato beetle in
Europe and the banana borer in Central
America. Its use in the U.S. was limited
to ant and roach traps.
Kepone is highly persistent in the envi-
ronment and becomes increasingly
concentrated as it moves through the
food web. Humans exposed to sufficient
quantities of this toxicant may sustain
serious medical complications, including
tremors, reproductive problems, and
liver damage.
Until 1975, there were 26 companies in
the U.S. producing 53 kepone-containing
products. Although EPA issued a stop
sale order in August 1975, it wasn't until
May 1978 that EPA banned further use of
kepone in any product
monitored in the tidal reach of the river
from Richmond to Newport News.
Since the onset of the monitoring
program, overall kepone levels in fish
have decreased although there have
been annual fluctuations.
Fish accumulate kepone relative to
their length of exposure to the pesti-
cide. Species-specific characteristics
such as feeding preferences, location of
spawning and nursery areas, migratory
patterns and metabolism also influence
the uptake, breakdown and elimination
of kepone. No correlation between the
size or sex of the fish to kepone levels
has been consistently found. Kepone
does have an affinity for b'pids, so
tissues with a higher fat content
incorporate more kepone. The brain or
liver of a fish, for example, generally
contains higher levels of kepone than
the edible meat of the fish.
Seasonal differences in kepone
levels in fish are evident in migratory
fish. Resident fish, such as largemouth
bass and sunfish display no seasonal
kepone variation since they remain in
the James River all year. On the other
hand, migratory fish species enter the
river in the spring, acquire kepone
through the food web and migrate out
of the river in the fall. As long as the
fish inhabit the river, they are exposed
to kepone. This exposure causes levels
in the spot, croaker, trout and bluefish
to rise the longer the fish remain in the
river.
Kepone levels are greatest in fish
collected from Hopewell to Burwells
Bay (Figure 3). Since sediment kepone
levels are higher in this area, more of
the substance is available to fish for
uptake. In other Bay areas, such as the
York and Rappahannock rivers,
Chickahominy Lake and Chesapeake
Bay, kepone is generally not detectable
in the fish.
The Current Status
With the discovery of widespread
kepone contamination of water,
sediment, finfish, and shellfish in 1975,
the state closed the James River to all
finfish and shellfish harvesting. After a
thorough review of the initial data, the
state permitted catches of shad, herring,
catfish and female blue crabs. The
fishing ban has been further modified
over the years as scientists gathered
additional monitoring information. In
1980, the sportfishing ban was lifted.
By 1981, commercial fishing resumed
for shellfish and all finfish except
striped bass. As the information base
expanded, the state again placed
restrictions on certain fish species. By
1984, it opened the river to spot fishing
and the restrictions were allowed to
expire in 1988 when kepone levels in
all fish remained consistently below the
FDA action level.
The water, sediment and finfish of
the James River are still contaminated
with kepone and scientists do not
predict complete cleansing of the river.
Fortunately, kepone levels in all areas
have decreased and should slowly
continue to drop over the years. Now,
the extensive and valuable fishery of
the James River can once again realize
its full potential. Meanwhile, monitor-
ing of kepone levels in the sediment
and fish will continue throughout the
contaminated reach of the James River,
providing the necessary assurance that
consumers of Virginia's seafood
industry remain protected.
Figure 3: In 1976, after LSP
stopped producing kepone, the
sediments in the James were
still heavily laden with the
toxic substance (dot size
corresponds with concen-
tration). Eleven years later,
levels of kepone at the same
stations were non-detectable.
The finfish show elevated
kepone levels In their tissues
throughout the 1970s. While
dropping below the FDA
action level in bluefish and
spot after 1980, the substance
persisted in the striped bass.
Kepone in the James River
In the Sediment (1976)
Values vary from .03 - .80
parts per million of kepone
Newport News
0.0
In the Finfish
Bluefish
StrpedBass
Spot
Norfolk
1976 1978 1980 1982 1984 1986 1988
31
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owards the Future
1989 STATE OF THE BAY
Monitoring key indicators that
define the Bay's health, as well as the
major pollution sources we are
attempting to control, will continue to
play a crucial role in marking our
progress and refining our plans well
into the next century. The next
milestone for use of the monitoring
information will come in 1991 when
Bay managers and scientists will
reevaluate the current bay wide nutrient
reduction strategy.
1991 Reevaluation
Top government officials in the Bay
region made a bold decision in 1987
when they committed to a 40%
reduction of nutrients entering the Bay
by the year 2000. While this step was
clearly needed in the Bay's restoration,
they also recognized that more defini-
tive information on the status of the
Bay, its response to past management
actions and projections of its response
to new initiatives would soon be
available. The signatories to the 1987
Bay Agreement, therefore, agreed to
reevaluate the nutrient reduction
strategy in 1991.
Findings from the analysis and
interpretation of Chesapeake Bay
Monitoring Program data will be a
cornerstone in the reevaluation process.
Monitoring information will provide
quantitative profiles of both water
quality and living resources for each of
the Bay's major basins. By coupling this
information with the monitoring of
nutrient loadings and the most current
thinking on water quality goals,
managers will develop a set of nutrient
reduction strategies for each basin.
These strategies can then be tested in
the 3-dimensional mathematical model
of the Bay which would not have been
possible without the comprehensive
water quality monitoring program.
The Chesapeake Bay Monitoring
Program will have three critical
functions in the 1991 Bay wide Nutrient
Reduction Strategy reevaluation:
Provide Bay managers and the
public with insights on past trends
(1950s-1980s) and the current
status of water quality, habitat qual-
ity and living resources through
analysis of the comprehensive
Chesapeake Bay database for the
tributaries and mainstem Bay;
Provide measures of the "environ-
mental effectiveness" of the
nutrient reduction approaches
implemented since 1984 through
analysis of nutrient loadings,
ambient water quality and the
abundance and diversity of living
resources.
Provide the data needed to develop
and calibrate the time-variable
water quality model of the Bay and
to assist in formulating the nutrient
reduction scenarios which will be
tested with the model.
An information baseline is now
firmly established with the recently
instituted programs and trends are
emerging. While maintaining the
current monitoring programs to pro-
vide the consistent information that
long-term management requires, we
also need to be responsive to emerging
issues demanding our immediate
attention. Some of the topics which will
likely be the focus of additional
monitoring and research follow.
Atmospheric Loadings
Worldwide, scientists have become
increasingly concerned over atmos-
pheric deposition in the past several
years as they continue to document the
far-ranging effects of acid rain and
aerial deposition of toxicants and nitro-
gen. The Chesapeake has not escaped
this form of pollution and scientists are
now evaluating the significance of
these "nonpoint source" nutrients and
toxicants. Research on the environmen-
tal impacts of acid precipitation has led
to questions concerning the contri-
bution of atmospheric deposition to the
nutrient budgets of lakes and estuaries.
With the discovery of pesticides and
other toxicants in lakes on uninhabited
islands in the Great Lakes and other
evidence of aerial transport of
toxicants, the need to explore further
this process of contamination is clear.
Findings from the limited atmos-
pheric deposition monitoring within the
Bay basin demonstrate the need for
further quantification of atmospheric
sources of nutrients and toxicants.
Future coordinated monitoring will
focus on:
• Quantification of atmospheric
contributions to nutrient and
toxicant budgets of the Bay and its
tributaries; and,
• Implementation of programs to
document the extent of stream
acidification in the Chesapeake Bay
watershed.
Developing Issues Toxicants
With implementation of the basin-
wide Toxics Reduction Strategy,
monitoring will play an increasingly
important role in targeting actions to
reduce the effect of toxicants on the
Bay. Existing monitoring programs
analyze sediment and tissue contami-
nant levels over wide geographic areas,
identifying "hot spots" on a baywide
scale. Under the Bay strategy, there
will be additional coordination and
targeting of toxicant monitoring
programs.
Chesapeake Bay monitoring of
toxicants in the 1990s will be used to:
• Determine the regions and com-
pounds of concern leading to the
design of more site and toxicant-
specific monitoring programs;
• Pinpoint the origin and quantify the
contribution of toxicants entering
the Bay and its watershed, includ-
ing point (municipal, industrial,
urban stormwater) and nonpoint
(agricultural, atmospheric, ship-
ping, urban runoff) sources; and,
32
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• Locate areas of ambient toxicity in
critical living resource habitats and
identify potential sources of the
toxicants using mobile bioassay
laboratories and field sampling.
Baywide Fisheries Management
The 1987 Bay Agreement called for
bay wide fisheries management plans
that would foster unprecedented coop-
eration among the various jurisdictions
charged with fisheries management
responsibility. Several of these plans
have already been adopted and they
point to the need for better monitoring
information—both for fish populations
and their habitats.
With existing habitat and living
resource monitoring data, scientists are
now making the links between habitat
integrity and the distribution and
abundance of plant and animal species.
Each species requires a distinct set of
habitat requirements—man can control
some factors although natural processes
play exceedingly important roles.
Through a better understanding of habi-
tat requirements and current conditions
we will be able to set water quality
goals that are more responsive to the
needs of the Bay's living resources.
Conclusion
Through concerted efforts to utilize
the best available monitoring infor-
mation, maintain long-term continuity
and be responsive to new issues, the
monitoring programs can provide the
guidance for the restoration and protec-
tion of the Bay's resources. Our recent
efforts to work cooperatively through-
out the region in solving the Bay's
problems have attracted attention as a
model for other regions in the nation
and other countries. As recent evidence
of atmospheric pollution indicates, we
also need to be cogni/ant of events oc-
curring outside the 64,000 square mile
drainage basin of the Chesapeake Bay.
Ultimately, the goal of the Chesa-
peake Bay Program is to restore the
Bay's plants and animals to healthy and
balanced levels. Management of these
living resources, stressed from fishing
pressure and declining habitat quality,
must continue to be supported by
sound, baywide monitoring data. With
a firmly established link between
findings from the monitoring programs
and refined management of the Bay
basin, we can be more confident than
ever in our prospects for success in
restoring and protecting the bounties of
the Chesapeake.
33
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