ABOUT THE DATA

The Connecticut River Watershed Atlas presents various themes of information in Geographic Information Systems (GIS) format as individual "map layers". Some map layers sharing the same theme are organized together in the Viewer under a category. For example, dams, streams, and lakes are in the WATER category. Within a category, there can be sub-categories of related data. In the Atlas Map Contents, category names and sub-categories are listed in all UPPERCASE letters.

Recent streamflow conditions at U.S. Geological Survey (USGS) streamgaging stations are always displayed in the map viewer. Click on the graphic below for more information.
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Information about all other data in the Atlas is presented below. Layers are listed as they appear in the Atlas Map Contents.

Map Contents

	Connecticut River Watershed -- A map layer depicting the physical boundary of the Connecticut River Watershed, as defined by the National Resources Conservation Service (NRCS).
	Mask area outside watershed -- This map layer highlights the Connecticut River Watershed by masking everything outside the watershed in gray. The layer can be turned off to allow for unobstructed browsing of map information outside of the watershed.
	STREETMAP USA -- A category containing "basemap" layers depicting political boundaries, roads, railroads, airports, and physical and cultural landmarks provided by Environmental Systems Research Institute (ESRI).
	WATER -- Dams, streams, lakes, and watershed boundaries are found in this category.
	STREAMFLOW DATA -- Streamflow measurements and estimates of mean annual streamflow are presented in this category.
	WATER QUALITY -- Information from the New England SPARROW nitrogen and phosphorus water-quality models are available in this category.
	ECOLOGY -- The Nature Conservancy (TNC) provides several map layers in this category showing ecological land units and managed (protected) areas.
	CENSUS -- 2000 U.S. Census Bureau population data is provided in this category.
	LAND COVER -- Land cover information from the National Land Cover Dataset is available in this category.
	TOPO MAPS -- Digital topographic maps are provided in this category.
	SAT_AIR_IMAGERY -- Satellite images and aerial photographs are available in this category.
	TOPOGRAPHY -- Colored elevation zones and shaded relief imagery are shown in this category.
	Background -- Northeastern USA states and Canadian provinces.

For instructions on accessing and displaying the map layers and viewing associated legends, see Working with layers and map contents.