In Massachusetts, when ownership is defined (by deed or Certificate of Title) to be "by" the ocean, sea, or other non-flowing, navigable water body, the "Ordnance 1647, Ancient Charter, pp 148" held that ownership is to the low water mark.
However, this ownership is subject to the rights of the public for "fishing, fowling, and navigation" from the Mean High Water Mark to the Low Water Mark or 100 rods (1,650 feet).
Other restrictions are created by the Wetlands Protection Act (Ch. 130 s.105) that regulates "dredging, filling, removing or otherwise altering, or polluting, coastal wetlands.
Not to mention the EPA, US Army Corps of Engineers etc etc..