- Causes of Future Sea Level Rise
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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.
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. Easements for access always include, by implication, the right to prevent the landowner from erecting structures that defeat the easement, so such an easement would also provide a property right to prevent shoreline armoring (or at least to travel along the shore inland of any armoring that is erected). 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.
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. 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. 
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.
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. 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
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. 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 sovereigns intent was ambiguous when the land was transferred. 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. For example, a statute or state constitutional amendment could amend a states 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. Nevertheless, legislatures have consciously altered property rights in states that limited the longevity of future interests in land, 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. 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).
 See supra §2.2. But c.f. Trepanier v. County of Volusia, 965 So.2d 276, 292–293 (Fla. App. 2007) (holding that the doctrine of custom could support a rolling easement theory if there was evidence that the custom was for the easement to migrate inland).
 See supra note 97 (cases holding that roads did not have a rolling easement) and Severance v. Patterson, No. 09-0387 (Tex. 2010). See also Trepanier, 965 So.2d at 292–293 (whether public easement resulting from custom migrates inland would depend on whether the evidence showed that people had customarily shifted their use of the beach inland as the shore erodes).
 See infra note 568 (citing a letter from the Texas Attorney General about new state requirement for waterfront owners to provide the state with rolling easements before beach nourishment can proceed).
 46 A.L.R. 1459. See, e.g., Collins v. Alabama Power Company, 214 Ala. 643, 108 So. 868. (citing the rule that the owner of the servient estate must abstain from acts interfering with the proper enjoyment of the easement by the owner of the dominant estate); Brown v. Alabama Power Company, 156 So.2d 153 (Ala. 1963) (issuing injunction against building a house that would obstruct drainage easement owned by power company); and Phillips v. Watuppa Reservoir Co., 184 Mass. 404, 68 N.E. 848 (1903) (holding that an easement to flood certain land precludes servient land owner from filling land if doing so prevents the flooding).
 E.g. U.S. v. Milner, 583 F. 3d 1174, 1190 (9th Cir. 2009) (in a case where boundary between two private parties is mean high water, [o]nce the shore has eroded so dramatically that the property owner's shore defense structures fix the ambulatory boundary, the upland owner cannot expect to permanently maintain the boundary there without paying damages to the tideland owner or working out an agreement with the tideland owner.)
 See Background section in Brannan v. State, No. 01-08-00179-CV, (Tex. App. Houston [1st Dist.] Feb. 4, 2010, pet. filed). That policy may be revised in the aftermath of Severance v Patterson, No. 09-0387 (Tex. 2010).
 See Scureman v. Judge, 747 A.2d 62, 68 (Del Court of Chancery, Sussex 1999) (rejecting towns theory that road along the shore had a rolling easement because roadway was on a specific dedicated parcel of land rather than on an easement across private land, and nothing in the conveyance suggested that the boundaries would roll); Town of South Hero v. Wood, 898 A.2d 756, 762 (Vermont) 2006 (rejecting towns theory that road along shore had a rolling easement because an implied dedication of an easement does not shift without the consent of the servient owner).
 Just as rolling easements along the beach often have some flexibility to allow people to continue occupying a home that encroaches onto the beach, an ambulatory boundary between two private landowners could include provisions for sharing the use of the land where feasible.
 E.g., Feinman v. State, 717 S.W.2d 106, 113 (Tex. App. 1986) writ refd n.r.e.). Parts of this opinion were later overruled in Severance v Patterson, No. 09-0387 (Tex. 2010) (We disapprove of courts of appeals opinions to the extent they are inconsistent with our holding in this case), but the rolling easement still applies under some circumstances. Id.
 See supra note 266.
 Some states have codified aspects of the public trust doctrine in statute (e.g. La. Civ Code Ann. Art. 451) or a state constitution (e.g. Wash. Const. Art. 17 § 1) The Texas Open Beaches Act specifies in great detail the migration of public access rights along the shore, see supra § 18.104.22.168, but it explicitly states that it does not alter property rights. See supra note 171, and accompanying text.
 For example, in Severance v. Patterson the Texas Supreme Court held that the legislature had been careful to avoid altering property rights in passing a statute that codifies a rolling easement in some circumstances. In 1969, the Legislature's Interim Beach Study Committee, chaired by Senator A.R. Schwartz of Galveston County, confirmed the view that:
[The Open Beaches Act] does not, and can not, declare that the public has an easement on the beach, a right of access over private property to and from the State-owned beaches bordering on the Gulf of Mexico. An easement is a property interest; the State can no more impress private property with an easement without compensating the owner of the property than it can build a highway across such land without paying the owner.
Severance v. Patterson, No. 09-0387 (Tex. 2010) (quoting Legislative Beach Study Commission, 65th Legislative Session, Footprints on the Sands of Time 17 (1969), emphasis added by the court). See infra §§ 4.1.3 and 4.2.1 for a discussion of takings and just compensation.
 See Preseault v.
This page contains a section from: James G. Titus, Rolling Easements, U.S. Environmental Protection Agency. EPA‑430‑R‑11‑001 (2011). The report was originally published by EPA's Climate Ready Estuary Program in June 2011. The full report (PDF, 176 pp., 7 MB) is also available from the EPA web site.
For additional reports focused on the implications of rising sea level, go to Sea Level Rise Reports.