In the previous two subsections we have considered conservation easements that prevent shoreline armoring and future interests in land that transfer ownership parcel by parcel. Here we explore the option of property owners making agreements to create “ambulatory boundaries,” that is, boundaries that migrate with a shifting shore. We have already seen that the boundaries for both ownership and public access resulting from the public trust doctrine are ambulatory (Section 2.2.2), and that for two decades people assumed that public access acquired by other means along the beach in Texas is also ambulatory (Section 3.1.2).

We now look at the possibility of voluntary agreements or changes in the law to accomplish the same thing for public beach access (outside of Texas), roads and other infrastructure, wetland migration, and water-dependent land uses. Our discussion of this option is shorter than the other approaches because there is less case law directly on point.

Public Beach Access. Affirmative easements generally do not migrate within a parcel, and an easement sold by the owner of one parcel does not burden land owned by other people. As we show in Chapter 2, access along the shore resulting from the public trust doctrine does migrate with shifting shores even when previously inland parcels become waterfront; but in most states, the access along the dry beach is not based on the public trust doctrine and probably does not migrate inland.[261] For a time, Texas courts held that public access obtained through other means also migrated as shores erode, but that rule was eventually limited to gradual erosion within a parcel.[262] The cases rejecting the rolling easement theory have not indicated that a rolling easement cannot exist, but simply that it had not been acquired.[263]

In a new community with public beach access, the developer could dedicate a rolling affirmative easement on the dry beach (instead of the more common public beach with fixed boundaries), before the parcel is subdivided. The deed conveying the beach access could say that the easement migrates with the vegetation line, or extends a fixed distance (e.g., 200 feet) inland of the mean high tide line and migrates as the mean high tide line migrates. For this rolling easement to be effective, it would have to either be dedicated to the public before the other parcels are sold, or explicitly reserved in the deed conveying individual parcels, or both. In existing communities that either lack public beach access or have a non-rolling beach access, a government agency could acquire a rolling beach easement through eminent domain, a purchase from willing sellers, or an exaction in return for building permits or beach nourishment projects.[264] Easements for access always include, by implication, the right to prevent the landowner from erecting structures that defeat the easement,[265] so such an easement would also provide a property right to prevent shoreline armoring[266] (or at least to travel along the shore inland of any armoring that is erected[267]). To ensure removal of pre-existing homes, the easement could be drafted to make clear that structures will be removed if they block access, similar to a policy that Texas has sometimes followed.[268]

Roads and Other Infrastructure. The potential impact of sea level rise on roads along the beach is similar to the impact on public beach access obtained by means other than the public trust doctrine. Erosion of the public roadbed does not automatically entitle the government to rebuild the road farther inland on private property, any more than beach erosion would entitle the public to sunbathe farther inland along those beaches. Courts have declined to find that a roadway had a rolling easement in cases where a rolling easement was not explicitly in the conveyance, while implying that the roadway could have been a rolling easement had that been the clear intent.[269] So in a new or redeveloping community, if a developer (or planning department) wants to ensure that the roadway can be relocated inland, then the initial dedication of the public roadway easement should clearly specify that it is a rolling easement which migrates inland as the shore erodes, whether slowly or by avulsion. Instead of defining the rolling boundary of public access as the vegetation line, this approach places the rolling boundary far enough inland from the vegetation line for a road as well.

As with rolling affirmative easements along a beach, a rolling easement for road access is more difficult to obtain in an existing community. There are many more landowners, and the land typically has been developed without buyers expecting that the road will be relocated landward. Nevertheless, obtaining such easements may be feasible if beach erosion is not likely to threaten the road for several decades, especially if existing development is set back from the street so that relocating the road would not immediately require moving houses.

One possible complication with a rolling roadway easement is how to handle the unpredictable fluctuations in the shoreline. Public access along a dry beach can respond instantaneously to shoreline migration, but roads and other infrastructure are fixed assets. The rolling boundary probably would have to be a significant distance inland from the dune line, for at least two reasons.

• The seaward edge of the rebuilt road would need to be somewhat inland from the dunes, so that the road need not be rebuilt every few years as the shore erodes.
• The landward edge of the rebuilt road would need to be somewhat seaward of the public access boundary, so that a modest temporary advance of the shore into the sea (by accretion or avulsion) would not leave the rebuilt road landward of the boundary when it moves seaward.

Other precautions may be necessary to address possible accretions or avulsions of new land. The easement conveyance could make it clear that the government may only pave roads seaward of the rolling boundary, but that the public also has access to any roadway originally built within the public easement, even if the boundary later migrates seaward of the road. Dune maintenance can move the vegetation line seaward even if the beach itself does not accrete. To prevent such activities from requiring an eventual seaward relocation of the roadway, the easement could include all land that is either, for example, within 100 feet from the vegetation line or within 300 feet from the mean high water line.

Other infrastructure along shorelines can also be dedicated with rolling easements, such as bicycle trails, sidewalks, and public utilities, as well as private driveways and utility connections.

Rolling Boundaries between Landowners. Instead of an easement, it may sometimes be advantageous for the actual property line to migrate inland. A governmental entity may be certain that it will have a variety of public uses for a parcel along the water, but not be able to articulate all of those needs in a proposed easement. Or a private owner who intends to operate a waterfront facility in an area with a retreat policy may need some assurance that the business can continue as the shore erodes. In such cases, a developer can convey a parcel in fee simple with a boundary that is, for example, 300 feet inland of the mean high tide line, and clearly state that the landward boundary migrates with the mean high tide line. Subsequent purchasers of inland parcels within the development would be subject to this rolling boundary. For most practical purposes, their risk of eventual relocation would be the same as the risk of anyone who buys land in a development subject to a rolling easement, except that the inland migration of the rolling waterfront business—rather than the wetlands or beach—would provide the immediate impetus for relocation. [270]

Similarly, a fringing marsh that is currently 200 feet wide, for example, can be preserved if a landowner conveys to TLC all land within 200 feet inland of the mean low water mark, specifying that the boundary migrates as the low water mark migrates. Some of that land will be below mean high water and hence (in most states) publicly owned. But if some of this land is also high marsh (above mean high water and privately owned), the rolling boundary will ensure that these wetlands remain within the ownership of TLC. Moreover, if a shore protection structure or fill project prevents the wetlands from migrating inland as the mean low water boundary retreats, the inland boundary of the TLC lands will migrate onto dry land, even though the fill will prevent the mean high tide line (and hence the public trust land) from migrating inland. TLC could then restore the land to its natural elevation and/or remove the structures.

As with a recorded rolling easement, the ambulatory boundary of any purchased conservation lands can only migrate as far as the inland boundary of the parcel whose owner conveyed this tract, because owners can only convey what they own.

Public Trust Doctrine and other Legal Doctrines. A landowner or government agency may go to court and ask for an easement or a property line to be adjusted inland, or for a shore-protection structure to be removed, on the grounds that the rolling easement is already part of the common law.[271] Such a holding is beyond the power of state and local governments, conservancies, and citizens to necessarily achieve. But the possibility that this will happen is part of the context of any rolling easement policy. The common law sometimes does evolve to address new situations. In Texas, the state government originally persuaded courts to recognize that public easements along the shore are “shifting and rolling easements” based on the state’s common law, not the Texas Open Beaches Act.[272] Florida courts have also implied that easements may roll under limited circumstances, based on the common law.[273]

In Washington State, a Native American tribe persuaded a court that there is a rolling easement along shores where the United States owns the tidal lands in trust for the tribe. The court balanced the interests of the property owners on the landward and seaward sides of mean high water, and suggested that the right to shore protection of the upland owners is limited by the interests of the tribe in the landward migration of the tidelands.[274] Although the laws of different states have many similarities, there are also differences in how littoral property rights have evolved.

The public trust doctrine has occasionally been construed as limiting the property rights of landowners who obtain public trust lands, if the sovereign’s intent was ambiguous when the land was transferred.[275] Hence it is possible that in some states this doctrine would be construed as implying that when the state land office (or King) granted the land to the original owner, the government did not vest the owners with a property right to hold back the sea, which would have thwarted the intent of the original decision to retain the tidelands in trust for the public. The reason that governments, land trusts, or citizens may want to consider recorded rolling easements to preserve wetlands and beaches is not that property owners otherwise have a right to hold back the sea, but rather that (a) there is legal uncertainty about this question, which a rolling easement can resolve, and (b) whether there is a property right or not, (i) land trusts, individuals, and governments without regulatory authority can prevent shore protection by obtaining rolling easements, and (ii) even agencies with regulatory authority may find the necessary community consensus easier to achieve with a rolling easement than through regulation.

Statutes and State Constitutions. Property rights are a matter of state law. While state courts generally determine what property rights are, state legislatures can adjust property rights as needed unless precluded by the state constitution, in which case the state constitution can be amended.[276] For example, a statute or state constitutional amendment could amend a state’s public trust doctrine to provide public access to the dune vegetation line however it may retreat. Legislatures are generally reluctant to alter property rights because doing so might require paying “just compensation” to the affected property owners.[277] Nevertheless, legislatures have consciously altered property rights in states that limited the longevity of future interests in land,[278] and federal legislation authorizes conversion of abandoned rail lines to multi-use trails even where land is supposed to revert when the railroad stops operating.[279] The potential near-term costs of compensating landowners would have to be weighed against the long-term costs of the alternative policies (e.g. shore protection or hazard-mitigation buyouts).