Aug 182017

Homes on Broad Beach

The California Ocean Protection Council and the California Natural Resources Agency have updated statewide guidance on sea-level rise to reflect new advances in ice loss science. Their new report, “Rising Seas in California: An Update on Sea-Level Rise Science,” notes that satellite data of West Antarctica show an increased loss of grounded land ice and accelerated loss of ice shelves, which buttress the grounded ice. If this continues, California’s shores could experience higher sea levels sooner that previously thought.

The problem is that the West Antarctic Ice Sheet lies on bedrock that is below sea level, in contrast to the Greenland Ice Sheet which is above sea level. If global warming is great enough to erode the floating ice that buttresses grounded ice, this would effectively uncork the bottle, unleashing an escalating and irreversible discharge of ice into the ocean. Such a loss could change the earth’s gravitational field and rotation, resulting in a higher rate of sea-level rise along California’s coast than the global average.

The precise magnitude and timing of when this would happen is unknown. But in a best-case scenario, research models show a seal level rise off La Jolla of about 6 inches by 2030 and one foot by 2050; while a worst-case scenario predicts the ocean will rise more than 1 foot by 2030 and 2 feet by 2050. The most extreme water-level increases will come after 2050, when ocean levels off Southern California could reach 2 to ten feet above 2000 levels by 2100.

The concern around an increased rate of sea level rise adds a new layer of legal complexity and overlaps current coastal planning. Even in the absence of sea level rise, poorly planned coastal development can be in harm’s way and affect public interests along the coastline. If not proactively and effectively managed, coastal development has the potential to reduce coastal access and degrade, destroy, and perhaps even privatize shorelines and tidelands.

Which brings us to the Public Trust Doctrine.

The Public Trust Doctrine is an ancient legal doctrine that goes back to Roman Law, under which some waters, tidelands and wildlife resources of the state are held in trust for all of the people, and the state acts as the trustee to protect these resources for present and future generations.

In California, this doctrine extends to the protection of navigable surface waters, to non-navigable tributaries of those waters, to aquatic resources, and to birds and other wildlife. Additionally, the courts have added the right of public access, and protection of the environment and recreation. Most importantly, this common law doctrine allows any person to bring a lawsuit against the state if it fails to fulfill its duty as trustee to manage these protected resources in accordance with the doctrine.  So how will the Public Trust Doctrine apply to private properties facing sea level rise?

In an effort to provide guidance to state and local governments, Stanford University’s Center for Ocean Solutions published two documents: Consensus Statement on the Public Trust Doctrine,  and The Public Trust Doctrine: A Guiding Principle for Governing California’s Coast Under Climate Change in July 2017. Authors included former leaders of the State Lands Commission, the California Coastal Commission, the California Department of Justice, the San Francisco Bay Conservation and Development Commission; as well as representatives of local government and a few academicians. The group met over the course of a year to develop a consensus interpretation of how the Public Trust Doctrine could apply to sea level rise, since it has not been fully fleshed out in the courts.  And because it’s a common law doctrine, the ultimate arbiter will be the courts.

Don Gourlie

One of the co-authors of the consensus statement, Don Gourlie, who is an Early Career Law & Policy Fellow at the Center for Ocean Solutions, reviewed the highlights in a webinar on August 16. He said that one of the main challenges the group focused on was the mean high tide line.

In 1935, the Supreme Court in 1935 defined the coastal property line as the mean high tide line, which is, of course, ambulatory. California courts have held that a coastal landowner’s property boundary continues to change because of the naturally changing location of the mean high tide line. The courts; however, have not reported cases specifically addressing the legal effect of permanent submergence on open ocean coastlines.

The mean high tide line is found by determining the average elevation of all high tides over the course of 18.6 years (one lunar epoch) and surveying where that elevation rests on the shore from time to time. A recalculation is due in 2022, and based on tide gauge data from around the state, it’s expected that the mean high tide elevation will increase a few inches through most parts of the state. When that occurs, the surveyed location of the property boundary will also change. The concern is that because this line in the sand, as it were, is so ambulatory, surveyed locations at any given point in time may not be useful in making long-term decisions about permanent structures.

The group suggested improving the way the mean high tide is located by increasing the number of tide gauges or surveys over a period of time to measure a boundary’s range of movement, and provide more resources for the State Lands Commission and other groups tasked with conducting those boundary determinations.

The mean high water line, or mean high tide line, is the boundary between public tidelands and uplands in California.

Four dynamic processes and how they may change the location of the mean high tide line.

Also, the ambulatory nature of the boundary is not very well understood by either the general public or relevant state agencies. That’s because property rights are assumed to have defined boundaries. Getting that information out there is important, which the group suggested could be done through through legislative discussion as well as disclosures of risks in coastal development permits.

Another problem is that the mean high tide line as a standard is actually challenging to apply on the open coast and not fully protective of public trust resources. The standard was initially developed through the federal courts and was applied in protected bays where there’s not much wave run-up. This and any issues relevant to the use of the mean high tide line on California’s open coast would benefit from discussion at the legislative level.

Local governments are likely worried that property owners will sue for losses due to erosion, inundation, and migration of the mean high tide line. On this, the group entirely agreed that the Public Trust Doctrine—as a background principle of property law in the state—would be a complete and successful defense to taking a claim. “What’s more likely to be challenged,” Gourlie said, “is if the state decides to regulate areas that are currently upland or private property that is likely to become public land in the future due to sea level rise.”

Seawall along Broad Beach

The group also tackled the issue of how permanent structures like seawalls would affect the movement of this boundary. Though there’s no California case on point to this effect, they noted that there are cases in other jurisdictions, as well as principles of property law recognized in California case law, which indicate that the placement of a physical structure that halts erosion or halts landward movement of water does not fix the legal shoreline boundary.

Once public trust tidelands are located, they need to be protected. “Identifying which areas should be included in the public trust is key,” Gourlie said. “Once that’s in place, government agencies should be systematic about considering and analyzing the expected effects of an action or decision on public trust resources; and not grant permanent grants that my adversely impact public land in the future.”

Other highlights:

  • Just as homeowners are required to clear space around their homes for fire prevention, we should protect our dynamic coastlines by not allowing activities that will encourage potential hard armoring of the coastline or the need to defend ourselves from sea level rise especially since this threat can be easily avoided. For activities that don’t take place on public trust land but affect them, decision makers should not undertake or authorize uses of uplands without appropriate safeguards for nearby public trust resources and uses.
  • Decision makers may need to review past decisions in response to new evidence concerning effects on public trust resources and uses and should retain this right to review. It’s also important to not grant permanent rights that may adversely impact public lands in the future.
  • Decision makers must consider and assert public interests in statewide policy making and long-term planning (e.g. creating or revising local coastal programs, local general plans, etc.).
  • Coordination among decision makers is essential, especially when locating shoreline property boundaries, in order to minimize conflict and avoid wasting resources.



Griggs, G, Árvai, J, Cayan, D, DeConto, R, Fox, J, Fricker, HA, Kopp, RE, Tebaldi, C, Whiteman, EA (California Ocean Protection Council Science Advisory Team Working Group), Rising Seas in California: An Update on Sea-Level Rise Science. California Ocean Science Trust, April 2017.

Sanda Mazza, Extreme sea-level rise could wreak havoc on California coast, experts warn,  April 18, 2017.

Environmental Law Foundation, et al., California’s Public Trust Document.

Center for Ocean Solutions, Story: The Public Trust Doctrine: A Guiding Principle for Governing California’s Coast Under Climate Change,  July 1, 2017

Center for Ocean Solutions, Consensus Statement on the Public Trust Doctrine: A Guiding Principle for Governing California’s Coast Under Climate Change, July 2017

Center for Ocean Solutions, The Public Trust Document: A Guiding Principle for Governing California’s Coast Under Climate Change, July 2017

Don Gourlie, Webinar: Public Trust Doctrine, Coastal Land Use, and Sea Level Rise, August 16, 2017


  1. Homes on Broad Beach, Mary Ann Wilson
  2. Don Gourlie,
  3. The mean high water line, The Public Trust Document: A Guiding Principle for Governing California’s Coast Under Climate Change, p. 17
  4. Four dynamic processes, The Public Trust Document: A Guiding Principle for Governing California’s Coast Under Climate Change, p. 18
  5. Seawall along Broad Beach, Mary Ann Wilson

  2 Responses to “Rising Sea Levels and the Public Trust Doctrine”

  1. Wow great article, Thanks!

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