Property fronting on navigable waters is delineated differently from landbound property. A waterfront lot line is subject to constant change as sand builds up on or waters recede from the shore. Every time a waterfront lot is surveyed, that line is redrawn to coincide with the "mean high-water line" (MHWL), which is the average location of the edge of the water at high tide measured over a 19 year period. Lands that lie below the MHWL, submerged or not, are sovereignty lands held by the State in trust for public use.
Using the MHWL for the lot line guarantees that a waterfront land owner's access to the water for bathing, fishing, viewing and navigational purposes will not be lost to the normal and natural changes of shorelines. Implicit in this guarantee is the potential benefit of an increase in the size of a waterfront lot when sands accrete or water levels recede and the potential risk of a decrease (or even a total loss) of a lot when shores erode or water levels rise.
When such lands-in-flux front along flowing rivers or streams, the principles which determine their legal usage are called "riparian rights," from the Latin ripa for "bank." In Medieval Latin terra riparia was the land adjacent to a river-bank. On shores of oceans, seas, and lakes they are called "littoral rights," from the Latin litus for "seashore" and its adjective form littoralis. In cases and statutes, however, the term "riparian rights" is widely used for both instances.
Not every change in the MHWL will alter the lot size, as reparian rights apply only to the slow and natural changes that are all but imperceptible as they occur. They do not apply to changes that are sudden or to those caused by beach improvements of riparian owners or the State, because those are actually just additions to or transfers of sovereignty lands. Thus in restoration projects an Erosion Control Line is fixed at the old MHWL. All sands added seaward of the line and future accretions are open to public use. A Florida statute preserves the riparian owners' rights of access, boating, bathing, fishing, and viewing, etc. across renourished areas, but not the right to own future accretions.
Since interference by government with riparian rights could constitute a "taking" in violation of the Fifth Amendment, the State may not add sand landward of the MHWL without obtaining the authority to do so from the owner or by eminent domain proceedings.
Riparian rights also have important implications for the islands' non-riparian owners and visitors who want to enjoy the public waters and shorelines, because they divide the beaches into public and private areas. Although one can only estimate the probable location of the current point at which private property begins, a simple rule-of-thumb is: damp sand at high tide is public and dry sand is private, adjusting the line a little higher in times when the beaches are accreting, or a little lower in times when beaches are eroding.
Where there is no beach, the MHWL is drawn on the outer face of rocks or seawalls that limit encroachment of the water. All parts of such rocks or seawalls landward of the point where the line touches them are private property. Hence walking on a seawall that water touches can be trespass, walking on a narrow beach that emerges by it at low tide cannot.
Though these conventions for defining property along shorelines are well established and accepted, legal and philosophical conflicts persist over the public's rights, if any, to use the dry sand areas of riparian lands.
One side holds that owners of waterfront property have as much right to demand exclusive use of their own land if they so choose as any other property owner has. The other side maintains that an uninterrupted historical use of the beaches by the public can constitute grounds to restrain owners from interfering with continuation of such use. A half dozen different legal theories have been tried in order to establish such a public right, but so far none has proven to be broadly effective. It is not likely that this conflict between two fundamentally opposing philosophical views of property rights will be resolved in the near future.
In the meantime, these divisions on our beaches are tempered by a long-standing tradition of generosity by the beachfront owners toward the use of their riparian land by beachgoers who behave themselves at a respectable distance from the owners' homes. This continues in spite of many unanswered questions about potential owner liability. So far, only misbehavior such as loudness and littering or persistent encroachment into the personal living areas of a riparian owner has ever undermined that generosity by motivating the owner and neighbors to consider re-asserting a claim to the exclusive use of their riparian sands.
In any case, it is in the long-term interest of beachgoers to assume the role of guests when on the dry sand areas of the beaches and to take every opportunity to educate others about riparian rights, thereby contributing to the continuation of that delicate balance of generosity and civility which has proven to be so effective in sustaining the open character of our island shorelines.