Engineers and other technical staff must estimate high groundwater levels in order to maintain proper separation from groundwater when designing on-site septic systems under Title 5 (310 CMR 15.000 The State Environmental Code), stormwater management systems, and for other purposes.
The Cape Cod Commission's Technical Bulletin 92-001 "Estimation of High Groundwater Levels for Construction and Land Use Planning" (revised in 2006) provides a method to use current water level measurements at the project site in conjunction with monthly index well data to estimate the maximum seasonal high groundwater level.
The maps, reference tables, and computational forms are found in Technical Bulletin 92-001. For more information on general groundwater levels and trends, the United States Geological Survey maintains an observation well network for Barnstable County which is accessible here.
Barnstable Bourne Brewster Chatham Dennis Eastham Falmouth Harwich Mashpee Orleans Provincetown Sandwich Truro Wellfleet Yarmouth
Note: The linked maps are those provided with Technical Bulletin 92-001.