Aldrich & Lambrechts report

Table 1

Probable "Normal" Groundwater Levels

Time Period		Probable Average
Groundwater Level
Comments
Pre-1800; before
Back Bay was filled		El. 5.7 (BCB)
(mean tide level)		Back Bay was a tidal
estuary of the
Charles River
1880-1910;
after filling		El. 5.8 at
Charles River;
el. 8± interior		Above mean tide level
due to infiltration of
rainfall & snowmelt
1910-present;
after Charles River
Dam completed		El. 8 at
Charles River;
el. 9.5± interior		Charles River Basin
maintained at el. 8.0

Note: Assumes no loss of groundwater by pumping or by leakage into sewers, drains, foundations or basements; and no additions to groundwater from leaking water mains and other man-made sources.