document progress towards water quality goals;
determine needs for further treatment;
maintain the interest of project participants and staff;
develop and transfer technology;
reduce the number of inconclusive studies conducted;
address increasing information needs.
The manager should become familiar with the essential features of an effective
monitoring program. A thorough understanding of the water quality problem,
monitoring objectives, and expected results will help the manager make informed
decisions and oversee the total water quality project. Because the manager may
be the only person involved in the monitoring program who has a big-picture
perspective of the overall program, he or she plays a key role in sustaining a
coordinated monitoring program that is effective for its intended purpose.
Management objectives may include restoring or protecting the uses of a water
resource or improving its ecological condition. In turn, a monitoring objective
must be related to the management objective and defined so sampling will support
the information needs of the manager. The monitoring objective specifies the
approach for monitoring a water quality variable, measuring pollutant loading
rates, or evaluating other measures of ecological integrity. Monitoring can
document pollutant sources or impacts or can help to justify the expenditure of
private or public funds on remediation or protection.
generally employs a fixed station network with long-term systematic sampling to
evaluate factors important to management.
A different approach to planning and design is generally required for NPS
monitoring compared with traditional point source (PS) monitoring. Typically PS
pollutants are diluted by the receiving stream such that high stream flows result
in low pollutant concentrations. Point source discharges may also vary with the
industrial process, time of day, and day of the week. Runoff and other land-based
pollutant transport mechanisms may have limited effect on PS pollutants but
stream physical, chemical, and biological processes remain important. Therefore,
source monitoring stations
stations for PS load monitoring are generally located near and downstream from
should be located downstream and
the known outfall.
drive NPS pollutant transport, the high variability
Because runoff and
of the process reflects such factors as weather, land use, and watershed charac-
below areas where targeted
teristics. Runoff and high stream flows can result in high pollutant concentrations.
and comprehensive land treatment
source pollutant concentrations vary by source type (land use), location
of source, transport mechanisms, and they are influenced by trapping in the
is planned, because subtle impacts
watershed and in-stream processes. Careful placement of monitoring stations is
to detect. More stations
required to account for these factors.
source monitoring stations should
or a more detailed monitoring
be located downstream and near major pollution sources, directly below areas
where targeted and comprehensive land treatment is planned, and where improve-
program may be required to assess
ments in water quality due to land treatment are expected to be greatest, because
NPS pollutants or
subtle impacts are difficult to detect.
of PS and NPS pollutants.