The Shawsheen River basin is located in Essex and Middlesex Counties and includes all or part of 12 towns and the city of Lawrence. Topography is low, with altitudes that range from 10 ft at the mouth of the Shawsheen River to 250 to 300 ft above sea level at the top of small hills along the drainage divide.

Unless otherwise noted, the following description of the water resources of the Shawsheen River basin is based on Hydrologic Investigations Atlas 614 (Gay and Delaney, 1980a).