Watershed Maps

The Assabet and Sudbury Rivers both start in Westborough and flow north until they meet at Egg Rock in Concord, Massachusetts, and become the Concord River. The Concord flows north to the Merrimack River in Lowell, Massachusetts, and into the ocean at Plum Island in Newburyport, Mass. This watershed is also known as the Concord watershed or Concord Basin. Click the watershed map for a downloadable version.

Other maps of the watershed:

OARS' sampling sites

On-line recreation maps of the Assabet, Sudbury, and Concord Rivers.

Maps by sub-basin:
Maps of the tributary streams of the Assabet River watershed. Used with permission from UConn's NEMO project.

Assabet headwaters, Westborough
Cold Harbor & Hop Brook, Northborough
North Brook, Berlin
Fort Meadow Brook, Marlborough
Danforth Brook, Hudson
Elizabeth Brook, Stow
Nashoba Brook, Acton
Taylor Brook, Maynard
Spencer Brook, Concord

Surficial geology of the Assabet River

Surficial geology describes the sand, gravel, soils, rocks, and other loose material that lie on top of the bedrock of New England. Because bedrock seldom yields enough water for a public supply well in Massachusetts, public water supplies typically are found in the surficial deposits. Of the various formations, the stratified sand and gravel deposits left by the last retreat of the glaciers are the most important aquifers for public water supply. Mapping the surficial geology gives geologists and hydrologists information about the ability of an area to store groundwater and provide baseflow to streams and rivers. The data layers for this map are from Mass GIS.

Assabet headwaters, Westborough
Hop Brook, Shrewsbury & Northborough
Cold Harbor Brook, Northborough
North Brook, Berlin
Fort Meadow Brook, Marlborough
Danforth Brook, Hudson
Elizabeth Brook, Stow
Nashoba Brook, Acton
Taylor Brook, Maynard
Spencer Brook, Concord