Physical/Chemical Monitoring: Rivers
Historically, river surveys were typically performed during low-flow, dry-weather conditions which generally represented the worst-case scenario with respect to the assessment of impacts on receiving water quality from point discharges. Today, increased attention is given to the identification and control of nonpoint pollution, and survey methods are changing to reflect this shift in emphasis. For example, wet-weather sampling may provide the most reliable information pertaining to nonpoint pollutant loadings from stormwater runoff and, when compared with dry-weather survey data, may further distinguish the effects of point and nonpoint pollution sources. Surveys are conducted every five years to update old information, and to examine the effectiveness of remedial actions such as treatment facility improvements, or implementation of Best Management Practices (BMPs) for controlling nonpoint sources of pollution.
River surveys are sometimes supplemented by wastewater discharge sampling which serves to document pollutant loading from point sources to the river at the time of the survey, and to assess compliance with NPDES discharge permit limits. In addition, stream discharge measurements may be made to supplement data from USGS stream gages. Discharge measurements provide data for the calculation of pollutant mass loadings, as well as for assessing the impacts on stream biota of low-flow conditions resulting from drought and/or water withdrawals.
MassDEP's Lake Water Quality Monitoring Program was formally initiated in 1974 and was significantly expanded in its scope during most of the 1980s. Historically, limnological sampling was conducted to: a) determine baseline lake conditions, b) monitor post-implementation projects, and c) respond to public concerns about lake problems. The focus of monitoring has changed over time and lake monitoring has been incorporated into the Watershed Approach. Lake monitoring is now conducted in the context of a review of issues within each basin. While overall lake monitoring is less than at the peak of the program, the monitoring conducted is targeted in the highest priority areas.
Lake sampling by DWM is now primarily limited to biological surveys of the macrophyton communities and "in-situ" measurements using metered probes. Baseline surveys by MassDEP are occasionally scheduled under special request or to provide data for TMDL development. A baseline survey is generally conducted in one day and consists of bathymetric mapping of the lake; physical, chemical and biological sampling of the open water areas, tributary stream(s), and outlet; and a quantitative and qualitative mapping of the aquatic macrophyton community in the lake. The primary purpose of this survey is to estimate lake trophic status and identify any point and nonpoint sources of pollution. The lake is sampled during the summer months when productivity is high.
Less intensive "synoptic" surveys have two primary goals. First, they provide information necessary to make a minimum assessment of lake quality. Second, they are used to document the spread of several non-native and potentially nuisance aquatic plant species that are known to be present in Massachusetts.
While MassDEP has performed some coastal monitoring in the past, this is not a major component of the monitoring program at this time. However, other Federal and State agencies, as well as local entities, do maintain coastal monitoring programs. For example, DMF performs monitoring to support shellfish resource management decisions, and to contribute to their periodic "Monograph Series" of marine resource assessments. In addition, the Massachusetts Water Resources Authority (MWRA) performs extensive monitoring to support outfall siting and Combined Sewer Overflow (CSO) management decisions, as well as to demonstrate the effectiveness of ongoing pollution control efforts. Finally, targeted research has been conducted through the National Estuaries Program to support the development and implementation of Comprehensive Conservation and Management Plans (CCMP). These include the Massachusetts Bays Program and the Buzzards Bay Program .
In 1996, the Massachusetts Office of Coastal Zone Management (MCZM) initiated a Marine Monitoring and Research Program (MMRP). Much of MCZM's initial emphasis has been placed on gaining information necessary to implement BMPs for the improvement of the ecosystem health of coastal embayments.