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STUDY DESIGN OF THE NEW ENGLAND COASTAL BASINS
The New England Coastal Basins (NECB) Study Unit was one of 15 NAWQA studies that began in Federal fiscal year 1997 (October 1996). Study planning, design, and analysis of existing data were done during the first 2 years, which was consistent in all NAWQA study units. After the 2-year planning period, surface-water, ground-water, biological, and ecological data were collected intensively for 3 years (termed the high-intensity phase, or HIP). A summary of the NECB study during its first deacde is contained in the report by Robinson and others, 2004. A low-intensity phase follows for 7 years, during which water quality is monitored at a selected number of ground-water sites and stream sites assessed during the HIP sampling years. This combination of high and low-intensity monitoring phases allows the NAWQA Program to examine trends in water-quality conditions over time. In 2009, the second decade of study activities for the New England Coastal Basins begins, starting with one year to plan study activities, and followed by a 4-year HIP sampling phase.
FIRST DECADE (CYCLE I): FOCUS ON OCCURRENCE AND DISTRIBUTION
National NAWQA Program
The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) is designed to describe the status of and trends in the quality of the Nation's ground-water and surface-water resources and to link assessment of status and trends with an understanding of the natural and human factors that affect the quality of water. The design is based on balancing the unique assessment requirements of individual hydrologic systems with a nationally consistent design structure that incorporates a multi-scale, interdisciplinary approach for ground water and surface water. By linking assessment of status and trends with an understanding of processes and causes that operate at various spatial and temporal scales, NAWQA can contribute most meaningfully to policies and management actions that improve water quality.
First Decade: Occurrence and Distribution Assessment. The first decade of the NAWQA program, called 'Cycle I', focused on the occurrence and distribution of contaminants. This component characterizes the broad-scale geographic and seasonal distributions of water-quality conditions in relation to major point and non-point contaminant sources and natural or background conditions. A key objective was to fill gaps in existing data for each Study Unit. Design features, such as chemical constituents measured, media sampled, and spatial and temporal resolution, were consistent among the Study Units. The Occurrence and Distribution Assessment was the largest and most important component of the first 3-year intensive study phase in each Study Unit and served as the basis for the design of assessments of long-term trends and changes and of more detailed case studies of specific water-quality issues.
For background on NAWQA sampling design, see Design Components.
Read more about the National NAWQA Program.
NECB Surface-water monitoring activities
Surface-water-quality monitoring activities in the NECB study unit during Water Years 1998-2001 (within the first decade of NAWQA) were intended to focus on the following issues:
The majority of surface-water-quality activities occurred in drainages entirely or primarily located in the Northeastern Coastal Zone ecoregion, because it contains over 80 percent and 90 percent of all urban and new urban lands, respectively, in the study unit (WRIR 98-4249). This translates into greater population and drinking water use in this ecoregion than the other ecoregions. Focusing on streams in the Northeastern Coastal Zone allowed the study to provide more thorough assessments of the effects of new and old urban land uses on stream water quality and aquatic biota. Our Liaison Committee identified these effects as being of great importance.
NECB Ground-water monitoring activities
Like the surface-water activities, ground-water activities of the NECB study, during 1998-2001, were identified in meetings with Liaison Committee members, discussions with other State and Federal agencies and NAWQA program specialists, and via retrospective analysis. As a result, the ground-water monitoring activities during Cycle I focused on the following issues:
Three sub-unit surveys and one land-use study were completed to address these issues. One sub-unit survey was conducted in the unconsolidated, glacial aquifer system; one in the calcareous metasedimentary bedrock lithogeochemical group; and one in a combination of the felsic igneous and other metasedimentary rock groups. (See publications list for more NECB reports).
SECOND DECADE (CYCLE II): TRENDS AND CHANGES IN WATER QUALITY
National NAWQA Program
A major focus of the NAWQA Program in its second decade is on regional- and national-scale assessments of trends and changes in water-quality of streams, rivers, and major aquifer systems in the Nation. The NAWQA assessments build upon previous findings generated during its first decade from 1991-2001 at the study unit scale. Primary goals remain the same; to characterize the status of surface-water (stream chemistry and ecology) and ground-water quality; determine trends at those sites that have been consistently monitored for more than a decade; and build an understanding of how natural features and human activities affect water quality. Analysis and reporting, however, will focus on trends, changes, and understanding at a larger “major river basin” and “principal aquifer” scale.
Second Decade: Trend and Change Assessment. Long-term trends and changes in water-quality conditions are assessed on a decadal scale in each Study Unit. Sampling strategies and the concurrent development of information on changes in land use, point sources, and other factors related to changes in contaminant sources are assessed. The Trend and Change Assessment will be based on data collected between intensive study phases and on data from successive 3-year intensive phases.
During Cycle II, NAWQA scientists plan to revisit 42 study units that were assessed during Cycle I. For Cycle II assessments, study units were selected that represent a wide range of important hydrologic environments, land uses, and sources of water used for drinking and irrigation purposes.
NECB Surface-water activities
In October 2001, the NECB study unit entered a period of reduced sampling activities known as the Low-Intensive Phase (LIP). Surface-water activities during the LIP consisted of monitoring for trends in nutrient and pesticide water quality and for suspended sediment in four of the nine routine fixed sites from Cycle I: the Charles River above Watertown Dam at Watertown, MA; the Merrimack River below Concord River at Lowell, MA; the Stillwater River near Sterling, MA; and the Aberjona River at Winchester, MA. Water samples were collected monthly at these four sites and analyzed for nutrients, pesticides, sulfate, chloride, and suspended sediment from October 2001 to October 2004. Periphyton samples were collected periodically during the summer "growing" season to assess changes in biomass in the rivers. In addition, annual surveys of macroinvertebrate and fish communities were conducted from 2001 to 2004 in the Aberjona and Stillwater Rivers and from 2002 to 2005 in the Charles River. From October 2004 to October 2006, only the Charles River was monitored for water quality and at a frequency of once every two months. Starting in October 2006, the Charles River will be sampled more frequently (about 21 times per year), but on a schedule of once every 4 years. The Charles River is scheduled to be sampled again in October 2011.
Second Decade (Cycle II): Surface-Water Trends and Changes Data
NECB Ground-water activities
Groundwater activites during Cycle II LIP consist of monitoring a subset of wells from each of three Cycle I networks (a land-use study of the effects of development on shallow ground water in the Boston metropolitan area, a fractured-bedrock aquifer study that focused on arsenic trace-element chemistry, and a study of sand and gravel aquifers throughout the study area). These wells will be sampled once every two years to determine trends in ground-water quality for nutrients, major ions, trace elements, volatile organic compounds (VOCs), pesticides, and 222radon. Five wells from each network were selected for resampling in 2003, 2005, and 2007. These same 15 wells, plus 2 additional 'reference' wells (installed in glacial deposits with minimal urban lands) that were added to the trend network in 2005, are scheduled to be sampled again in 2009 and 2011.
Second Decade (Cycle II): Ground-Water Trends and Changes Data