Draft
Objectives for Non-Tidal Water-Quality Monitoring
Defining the objectives of a monitoring program is an essential first step for data-collection
network design. The objectives define the purpose and scope of the monitoring program and in
that way provide the basis for determining if a given network design is adequate. For example, a
monitoring program with the objective of quantifying loading from first-order streams could
have a network design that is much different than a monitoring program with the objective of
determining compliance with water-quality standards. In either case, the objectives must be
defined in order to determine if a given network design will be adequate. Furthermore, the
objectives should be defined in sufficient detail to determine the criteria for an "adequate"
network.
In many cases, as they evolve over time, monitoring programs begin to be used for multiple
objectives. Objectives are often added to the existing network as new needs arise. Often, the
data-collection network is less than optimal for more than one objective, because it was not
designed for objectives that began after the network was in place. In such cases, the network
design should be evaluated periodically in order to determine if it is adequate for all of the
purposes for which it is being used. When there are multiple objectives, adequacy should be
considered separately for each in order to identify weaknesses and necessary improvements for
individual objectives. The criteria for data collection for all the objectives can then be combined
to develop the overall data-collection network.
The non-tidal water-quality monitoring network in the Chesapeake Bay watershed is an example
of a data-collection network that has multiple objectives, which have evolved over time. The
original network consisted of federal, state and local agency water-quality monitoring networks
that were designed separately with different (although often similar) objectives. Those individual
networks are now viewed as one data-collection network for the purposes of Chesapeake Bay
restoration. The Chesapeake Bay Program (CBP) Non-tidal Water-Quality Monitoring
Workgroup is now conducting an effort to evaluate the adequacy of the overall network for
addressing the objectives for which it is already being used. Where weaknesses in the overall
network are identified, recommendations will be made to the agencies that conduct the
monitoring in the hope that they will be able address the weaknesses.
Scope of Monitoring Objectives for Non-tidal Redesign
This document is intended to identify and describe the primary objectives of the non-tidal water-
quality monitoring network for use in Chesapeake Bay restoration. Once the objectives are
defined, criteria can be established that describe the characteristics of a network design that is
adequate for addressing the objectives being considered. Comparison of the necessary criteria

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with those of the actual monitoring network will provide a basis for evaluating the existing
network and for making recommendations for improvement.
The evaluation being performed by the CBP Non-Tidal Water-Quality Workgroup is primarily
focused on nutrients and sediment, which are considered to be the greatest problems for water
quality and ecological integrity in the Chesapeake Bay. Other water-quality constituents such as
toxic contaminants are also important and the need for monitoring of those constituents is
described in the CBP monitoring strategy. However, monitoring design for toxic contaminants is
beyond the scope of this work and objectives for toxic contaminant monitoring will not be
considered here. The Non-Tidal Water-Quality Workgroup recommends that a separate network
design effort be established for monitoring toxic contaminants.
This evaluation is focused primarily on water quality and related issues in the non-tidal part of
the watershed. Non-tidal living resource monitoring is also needed, but is not considered here.
Separate efforts by the Living Resources Sub-committee Monitoring and Modeling Workgroup
will address the need for living resource monitoring in the non-tidal part of the watershed.
Finally, this evaluation is focused primarily on basinwide water quality and loading to the
Chesapeake Bay. The objectives considered here will be those that consider a whole watershed
perspective as compared to more local issues such as TMDL's and local compliance with water-
quality standards. While such local issues are related to the water quality and ecological integrity
of the Bay, they will be quite variable across the watershed and outside the influence of the CBP.
Thus only the broad spatial scale objectives will be considered here.
Definition of Monitoring Objectives
The objectives for the non-tidal water-quality monitoring network are based on commitments
listed in the Chesapeake Bay 2000 agreement. Non-tidal monitoring data are necessary to
address a number of commitments. Among those are the following:
Nutrients and Sediments
3.1.1
• Continue efforts to achieve and maintain the 40 percent nutrient reduction goal
agreed to in 1987, as well as the goals being adopted for the tributaries south of the
Potomac River.
3.1.2
• By 2010, correct the nutrient- and sediment-related problems in the Chesapeake Bay
and its tidal tributaries sufficiently to remove the Bay and the tidal portions of its
tributaries from the list of impaired waters under the Clean Water Act.
3.1.2.5
• By 2003, work with the Susquehanna River Basin Commission and others to adopt
and begin implementing strategies that prevent the loss of the sediment retention
capabilities of the lower Susquehanna River dams.
Non-tidal monitoring data are essential for tracking the effectiveness of the 40 percent nutrient
reduction goal (3.1.1) for reducing stream loads. Combined with the watershed model, the data
can also be used for identifying reasons for observed responses of streams. Non-tidal monitoring
is also essential for developing management strategies that will lead to removal of the Bay from

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the Clean Water Act list of impaired water bodies (3.1.2) and to understanding and managing the
sediment retention capabilities of the lower Susquehanna River dams (3.1.2.5).
Specific uses of the non-tidal water-quality monitoring data for achieving the commitments listed
above include:
1.	estimating the amounts of nutrients and sediment that reach the Bay from non-
tidal parts of the watershed (load estimation);
2.	identifying the watershed sources and basin characteristics that affect nutrient
and sediment transport (load estimation);
3.	tracking temporal changes in concentration and loading, and relating them to
natural variation or management actions (trend analysis);
4.	relating temporal changes in loading to temporal changes in Bay water quality
(trend analysis);
5.	calibrating the watershed model in order to evaluate the potential benefits of
management action scenarios (calibrate watershed model);
6.	performing studies to understand the processes that affect nutrient / sediment
generation, loss and transport (research).
Generally, these examples and most others can be grouped into three categories: 1) load
estimation; 2) trend analysis; 3) watershed modeling and 4) research. The non-tidal monitoring
network should provide data that are adequate for these applications and ideally the network
would be designed for these applications. The current network, however, consists of the
combination of multiple smaller networks that were designed for other purposes. Thus the non-
tidal network evaluation is intended to identify gaps and weaknesses for the objectives described
above. More detailed discussions of these objectives are provided below.
Load Estimation
Much of the water-quality data that is collected is used to quantify the amount of nutrients or
sediment that is transported from the drainage above the sampling location. This information is
used to perform mass-balance studies to identify the predominant sources of nutrients or
sediment upstream or to quantify the amount going downstream for the purpose of evaluating
impacts there. Load estimation is a critical task for the Bay restoration because it forms the basis
for managing nutrient transport to the Bay.
For the load estimation objective, water-quality samples are usually collected in association with
a stream gage where continuous discharge data are available. Intermittent water-quality samples
are collected, transported to a laboratory and analyzed to provide concentration data. Generally,
concentration data are available in relatively low frequency, which may range from 10 to 50
values per year. Because concentration data are usually available in low frequency, statistical
tools are used to estimates stream loads. Most of these tools are designed to optimize the

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accuracy and precision of load estimates based on covariance between concentration and
discharge.
Some specific examples of load estimation include the following:
1.	The spatial distribution of load estimates are often related to the spatial
distribution of sources (e.g. - STP's) or basin characteristics (e.g. -
hydrogeomorphic region) to assess the importance of those features for
determining the amount of nutrient or sediment transport.
2.	Load estimates are often used to compare the export rates of different drainages
so that they can be ranked to set priorities for management actions.
3.	Load estimates are used to generally characterize watersheds in order to
communicate with the public such as in the web-based Watershed Profiles.
Water Quality Trends
Trend analysis is performed to evaluate temporal changes in measures of water quality. Trends
are usually analyzed to define statistically significant changes over time, the direction of change
and possibly the amount of change. Results of those analyses provide information to evaluate the
potential benefits or ineffectiveness of management actions or natural variations of which
mangers should be aware.
Trend analysis is generally performed by visually evaluating the time series of monitoring data
and by applying a statistical test to determine if any change is significant. Thus monitoring over
several years is required to identify trends. Some monitoring sites would be more advantageous
for this objective solely because a long historical record already exists. Stations for water quality
trends may require less intensive sampling regimes than those needed to estimate loads because
the higher frequency variations are less important to long term changes.
Watershed Modeling
Monitoring is required to estimate parameters for the watershed model being used by the CBP to
evaluate management scenarios. Scenarios such as the more widespread application of Best
Management Practices (BMP's) will need to be evaluated. Some scenarios will include activities
intended to ameliorate a specific type of environmental stress, such as erosion from fields or
stream banks. Other scenarios may have a more general scope, such as locating housing
developments away from streams and other critical habitats. The objective of this type of
forecasting is to permit the CBP to compare the contribution of management activities to
reducing nutrient and sediment loads. Still other scenarios will incorporate the continued growth
of the population of the watershed and the accompanying changes in land use. Modeling will be
used to forecast water quality as a consequence of future land use.
The number of calibration sites needed for this purpose is unclear, but in general, the accuracy of
the model will be improved by a larger number of monitoring stations that are broadly
representative. Such an array of sites could improve the capability of the model to discriminate

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between watersheds. Most of the current sites represent large watersheds with heterogeneous
land uses, whereas model calibration could be more precise when based on smaller watersheds
with homogenous land cover. Sampling regimes and station locations are dictated by the
requirements of the model, but generally the model requires calibration data for a variety of
substrates and land use types. Emphasis is given to sampling to estimate those parameters to
which the model is most sensitive. Specific land-use classes should be included to determine
how well the model functions over a wide range of land-use categories. Additional data may be
required to validate model performance.
Research/Education Uses
The results of monitoring are useful to researchers and educators. As the cohesiveness and
quality of the monitoring data improve, the data will become increasingly useful for determining
long-term changes in the Chesapeake Bay ecosystem. Several long-term changes in the
watershed are occurring now and will attract increasing attention as the shorter-term objectives
of the CBP are met. One of the most notable is the increase in urbanization accompanied by the
conversion of forest and agricultural land to housing. Another trend is the expected increase in
atmospheric C02 concentration, which may result in increases in primary productivity and the
sequestering of more nutrients in the non-tidal portions of the watershed. If the increase in CO2
is accompanied by an increase in global temperature, it is likely to produce a change in farming
practices as well as shifts in the composition of forested ecosystems. All of the trends listed
above will interact in ways that are very difficult, if not impossible, to predict. The monitoring
data will become an important tool to evaluate the effects of changing land-use as it interacts
with potential changes in global climate.
Long-term non-tidal monitoring data is also valuable in the study of small single-land-use
watersheds for the purpose of understanding processes that affect nutrient and sediment loading.
For example, long term monitoring of predominantly agricultural watersheds, combined with
other types of information, can be useful for understanding the processes that affect the transport
of nutrients and sediment from such areas. Similarly, long-term monitoring of predominantly
forested watersheds can be used to understand how nutrients and sediment might be transported
under relatively pristine conditions. Process oriented research such as that described for single
land uses can be valuable for the goals of the Chesapeake Bay program because it provides
information that supports the development of reduction goals and the improvement of modeling
tools. For that reason, long-term monitoring should be used to support such efforts whenever
possible.
For the reasons stated above, research is important for the goals of the Chesapeake Bay Program,
but is generally considered to be a secondary objective of the non-tidal water-quality monitoring
network. Various research efforts have used water-quality data from the network and it is
expected that this will continue in the future. However, research objectives can be quite variable
across the watershed and can change with time. Thus it is difficult to include research as a broad
objective for the design of a non-tidal water-quality monitoring network. The Non-Tidal Water-
Quality Workgroup would like to express support for the use of water-quality monitoring data in
research efforts and will provide support where possible. However, research cannot be
considered a primary objective for the design of the network and will not be used as a basis for
that purpose.

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