Before the State's recent monitoring initiatives commenced in the summer of
1984, certain segments of the Bay had been studied intensively for only
brief periods of time and often only in selected seasons. In one area,
chemical and physical measurements may have been taken. In other areas or
times, biological measurements may have been taken. This level of effort
may have been sufficient for the objectives of each of these studies but it
left many gaps in our understanding of the Bay.
The newly initiated OEP water quality monitoring program closes the
previously existing gaps by being comprehensive, maintaining a
Bay-wide perspective and having a long-term commitment.
It is comprehensive in its approach by including the most important
physical, chemical and biological measurements from a management and
scientific perspective. These measurements take place in a coordinated
fashion, in many cases at exactly the same times and places; data collected
in this way enhances our ability to interpret linkage between monitored
parameters.
Second, a Bay-wide perspective has been applied to the location of
sampling stations throughout the tidal tributaries and mainstem of
Chesapeake Bay. Existing programs, such as that in the Patuxent River, were
enhanced and incorporated into the expanded program while those regions
that lacked coverage are now included. As a result, every major tidal
tributary in the State is included in the present monitoring network, as
well as the mainstem from Havre de Grace at the head of the Bay to the
mouth of the Potomac River at the State line. The Bay-wide coverage reaches
beyond our state boundaries with similar efforts in Virginia and
Pennsylvania, coordinated by the three states and EPA. Bay-wide coverage is
necessary in order to effectively evaluate where and how pollution control
measures are working, to identify regions in need of additional remedies
and to better understand the fate and effect of pollutant inputs.
Third, this monitoring program has been constructed with a long-term
perspective, as mandated by a bill passed in the 1985 State legislature
which directs Maryland's OEP and Department of Natural Resources to
initiate and continue monitoring of the Bay's water quality and living
resources. In a system as large and complex as Chesapeake Bay, where
natural year-to-year variability can make trends difficult to discern,
several years of record are required to make reliable assessments from
monitoring programs. Further-more, the challenge of cleaning up Chesapeake
Bay is likely to continue well into the future, requiring continued
vigilance as added pressures impinge upon its shores.
Each component within the overall Water Quality Monitoring Program was
chosen with an ecological perspective to provide a comprehensive set of
important water quality indicators. While each component individually is
capable of providing an indication of Chesapeake Bay water quality, the
synthesis of information from all of these elements permits much more
precise and meaningful assessments to be made. Each of these components is
portrayed in Figure 5 and explained briefly below.
Figure 5. Components of the OEP
Water Quality Monitoring Program in the perspective of major ecological
relationships in Chesapeake Bay.
Chemical and Physical Properties - The measurement of chemical
and physical variables such as salinity, dissolved oxygen, suspended
sediment and nutrients, provides baseline data to characterize physical
properties of the system such as stratification and provide knowledge of
the levels and distributions of important pollutants. This element has the
most intensive spatial and temporal coverage and forms the foundation for
interpreting measurements from all other components.
Toxicants - Toxic pollutants, both metals and organic compounds, are
measured in the sediments where they tend to accumulate after being
discharged into the estuary. Levels in the tissues of benthic organisms are
also monitored as an indicator of accumulation in the food chain.
Plankton - Plankton include the microscopic plants and animals
suspended in the water column that form the base of the estuarine food web.
Thus, they are directly or indirectly crucial to the success of important
Bay resources such as fish and shellfish. These organisms are also
responsible for the symptoms of eutrophication, such as low dissolved
oxygen and decreased water clarity, that result from excessive nutrient
inputs.
Benthic Organisms - Benthic organisms, which live in or on the
bottom sediments of Chesapeake Bay, have a prominent role in the food web
as important components of fish and crab diets. They also mediate in many
processes occurring where bottom sediments interface with the overlying
water column. They are good indicators of Bay water quality, especially
local conditions, since they occupy a relatively fixed position on the Bay
bottom and respond to changes over both long and short time intervals.
Ecosystem Processes - Many of the important water quality indicators
are not static measures, but rather processes or rates that reflect the
dynamic nature of water quality in Chesapeake Bay. Several of these
processes were chosen as a separate element of the OEP program such as
sediment-water column exchanges of nutrients, oxygen and particulate
matter. Other important processes such as phytoplankton growth rates and
river inputs are included as part of other program elements.
Pollutant Inputs - The input of freshwater, sediment and nutrients
from the major rivers and point sources control water quality to a large
extent in the Bay and its tributaries. This component therefore becomes
crucial to an interpretation of Bay water quality and to track the progress
of management actions throughout the Chesapeake Bay basin. River input
monitoring is the major new initiative in the OEP program.
In assembling the monitoring elements described above into a unified study,
several design considerations were applied uniformly to insure success in
achieving the program's objectives.
First, no elements were considered for monitoring unless there was a sound
scientific basis for measuring the parameters that comprise a given
component. Where some uncertainty existed, literature reviews and pilot
studies were conducted before implementation to evaluate alternative
monitoring designs.
Second, the selection of sites to be monitored for each element was
designed to be representative of major regions in the mainstem and
tributary estuarine system. Other considerations in site selection, once
the representative nature of a location was satisfied, included important
habitats, such as striped bass spawning areas, and the availability of
useful historical data.
Third, frequency of monitoring was tailored to the known temporal
variability for given parameters to efficiently and effectively utilize the
resources available for monitoring. The more variable a parameter is
through time, the more frequently it must be sampled to provide an accurate
and precise measurement. For example, river loadings can undergo very rapid
changes during the course of a storm and therefore conditions must be
monitored several times a day during these events to provide an accurate
picture of loadings. At the other end of the spectrum are sediment
measurements that are more stable in character through time and are
therefore sampled only once per year.
The management of information generated by the program and the reporting of
results is a critical final step in the program design. Much of the effort
to date in this aspect of the program has been devoted to constructing a
reliable and responsive data base from which to draw upon for analysis and
interpretation. All data being collected is stored on computer-based media
for rapid access and manipulation. Rigorous quality assurance insures that
the data collected in the field and in the lab is reliable and meets the
intended needs of the program. Reporting of results from the monitoring
program is also proceeding as planned. Yearly data reports have been and
will continue to be forthcoming from each of the individual monitoring
components in a common format; these individual reports can be viewed as
the building blocks for subsequent, more synthetic data analysis efforts.
In future stages of the program, when the data base is sufficient to
achieve this more synthetic level of analysis, the results of individual
monitoring elements will be brought together to form a comprehensive
interpretation of Chesapeake Bay water quality. This synthesis of
information from all the interrelated indicators of water quality, is the
strength of the State's program. Following this report, at two year
intervals starting in the fall of 1988, there will be a technical synthesis
report of information from the monitoring program. A concise summary,
distilled from this technical synthesis, will be produced by the spring of
the following year.
 The
yearly data reports from each monitoring element, and the two levels of
synthesis every other year, will insure that all citizens, legislators,
managers and scientists can profit from the State's assessment of
Chesapeake Bay water quality.
The present suite of program components, sampling locations (Map 1) and
sampling frequencies represents an efficient and cost-effective design. One
could always point, however, to areas in the Bay without sampling sites for
certain variables of the additional information that could be gained with
more sampling trips. But, this thinking must be balanced by the benefit
that such additional information would yield for the expense involved. This
cost-benefit analysis was also a major factor in the selection of the
monitoring program design. The current design yields a practical and
technically sound program capable of reaching its objectives on a Bay-wide
scale and capable of being sustained for the time necessary to reach its
major objectives.
Map 1
Contents
a.
Preface
b.
Acknowledgements
1. Introduction
2. Understanding The Bay's Problems
3. Program Description
4. Chemical and Physical Properties
5. Plankton
6. Benthic Organisms
7. Ecosystem Processes
8. Pollutant Inputs
9. Management Strategies and the Role
of Monitoring
10. Glossary |
