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Tuesday, June 7, 2022

“Mean high tide” probably isn’t where you think it is

Seeking to Control Ever-Changing Environment, Shoreline Access Bill Requires Close Attention

By Nathan Vinhateiro and Janet Freedman / URI Coastal Institute

From James G. Titus, Rolling Easements, U.S. Environmental Protection Agency

Access to Rhode Island’s shoreline has become a major issue at the Statehouse this year.

Proposed legislation aims to set a standard that balances the public’s constitutional right to walk along the beach with the rights of private property owners on the coast.

Rhode Island is the Ocean State and its people have always passionately protected their access to the coast. From the Narragansett Indian Tribe’s deeply spiritual relationship with Grandfather Ocean, to the Rhode Island State Constitution, the sea and the shore are so integral to our state’s identity that they are held in trust for the people’s use.

But if the “shoreline” changes with each breaking wave, how do we draw a line in the sand for public access? Here’s what the science says on a very complex issue.

The current legal standard is from a 1980s Rhode Island Supreme Court decision. The court tried to use science to define where our so-called “shoreline privileges” could be exercised. The decision attempted to balance the rights of the public and coastal property owners by setting the boundary of public land at the “mean high water line” and defined how to go about determining that line.

But did the court actually solve the problem using science? No, because they failed to understand that the mean high water line is not the location where high tide meets the beach.  

Mean high water is a statistic. It’s the average of all the high tides, two per day over a 19-year period. And tides are measured at tide gauges, where there are controls to eliminate factors like waves, which push water up the shore when they break. On wave-dominated beaches like we have in Rhode Island, wind and waves push the water dozens of feet landward from the mean high water line under normal conditions.

Furthermore, beaches are landscapes in motion. Sand is pushed around by every wave, changing the shape of the beach, sometimes imperceptibly and sometimes dramatically. So the mean high water line can never be a permanent boundary because its location also moves as the beach changes shape.

University of Rhode Island scientists have shown that this line can migrate more than 100 feet within a few years even without a major storm. Simply put: Beaches are not a place where a fixed property boundary can be established.

Science also shows that the mean high water line is underwater for most of the day in Rhode Island. The URI Coastal Institute has been conducting monthly tide surveys since last July. The results show that the mean high water line is actually underwater or in the active surf zone most of the day and, even when the mean high water line is dry, the water laps very close by, just inches to a few feet away. 

So, using the Supreme Court’s decision, beachgoers would usually have to walk single file if they want to legally walk along the shore even during that limited time.

The intent of the earlier Supreme Court ruling was to use science to create balance between the public and private property owners on the shore. But in not considering waves, local winds and other coastal processes, the ruling essentially cuts out the public. 

Clearly this underscores the need for new policy that takes in to account the dynamics in the coastal environment and relies on easily identifiable features that can be understood by the casual beachgoer or property owner.

Rhode Islanders will be best served when our law acknowledges a simple truth: The coast is an ever-changing environment, one where boundaries cannot be fixed, no matter how precisely they can be calculated.  

Nathan Vinhateiro is assistant director of the URI Coastal Institute and Janet Freedman is a senior fellow at the URI Coastal Institute.