Few small cities have their geology discussed on the evening news as often as Del Mar. In February 2021, part of the bluff below the coastal rail line gave way. Emergency repairs ran into mid-2022. Then came a larger stabilization phase that kept crews, drill rigs and fencing along the cliffs for much of 2024, 2025 and 2026. Behind all of it sits a quieter, longer conversation about moving the tracks off the bluffs altogether.
If you own a home on the North Bluff or South Bluff, or in the hills behind them, it is natural to read each headline and wonder what it means for your house. This entry lays out the background: what the bluffs are made of, what the railroad work is, and where private homes fit in the picture.
The ground has a local name
Del Mar lends its name to a rock unit. The California Geological Survey describes the Eocene Delmar Formation as a dusky yellowish-green sandy claystone interbedded with coarse sandstone, named for its sea-cliff exposures here, and the U.S. Geological Survey’s records place a type section about two kilometers south of the old Del Mar railroad station. Torrey Sandstone, named for Torrey Pines, also forms bluffs along this stretch. Above those older rocks sit younger, looser terrace deposits.
That mix matters. Claystone and sandstone weather differently, and the loose material on top gives way more easily than the rock below. Add waves at the base, groundwater and runoff from above, and the result is a cliff that retreats in fits and starts rather than at a steady pace.
How fast is “fast”
When the emergency work wrapped up in 2022, SANDAG and the North County Transit District told KPBS that the Del Mar bluffs had eroded up to about six inches a year on average over the previous 25 years. Averages hide a lot. A stretch of bluff can sit for years with little visible change, then lose a large block in a single storm or after a wet winter. That is why the 2021 failure got so much attention: it was a sudden event on a slow-moving problem.
Why the railroad is the headline
The tracks along the bluffs are part of the LOSSAN corridor, the rail link between San Diego and the rest of the state, carrying both passenger and freight service. Keeping them stable is the reason most of the public work happens.
SANDAG reports that it and NCTD have completed five stabilization projects between Coast Boulevard and Torrey Pines State Beach, installing more than 380 support columns and investing in drainage. Phase 5, which ran from 2024 into 2026, added more columns, drainage improvements, new retaining walls, erosion control and native planting across a project zone of about 1.7 miles, from 15th Street to the bridge at North Torrey Pines Road. SANDAG lists Phase 5 as complete as of fall 2026.
Notice how much of that work is about water. SANDAG describes its approach as installing supports and directing stormwater runoff. The lesson for homeowners is the same one: water that soaks into the top of a bluff, or pours over its face, is one of the main drivers of failure.
The longer story: moving the tracks
Stabilization is described as a near-term measure. SANDAG says it is evaluating strategies to relocate the tracks off the bluffs entirely, and that the rail realignment project is in its environmental phase, studying alternative alignments under state and federal environmental review. The City’s 2018 Sea Level Rise Adaptation Plan, as summarized in the County’s hazard annex, also supports eventual relocation of the railroad off the South Bluff.
None of that has a firm end date, and alignments are still under study. For now, the practical takeaway is that the bluffs will remain an active public works zone for years, with the long-term plan changing as studies progress.
Where homes fit
Public stabilization work protects the rail corridor. It is not a review of the private lots nearby, and it makes no promises about them. A few points are worth keeping straight:
- The rules for private property are separate. The County’s hazard annex for Del Mar notes that the City’s coastal program prohibits development within 40 feet of a coastal bluff edge and requires real estate disclosure for properties in the Coastal Bluff Overlay and Floodplain Overlay.
- Different bluffs, different hazards. The annex maps the North Bluff and South Bluff for coastal bluff erosion, and the North Hills and South Hills for inland bluff erosion. A hillside home a few blocks inland can still sit on a mapped bluff hazard.
- Neighboring construction is worth documenting. Heavy work nearby is a good reason to record your home’s condition before and after: crack photos with dates, floor levels if you have them, and the state of walls and drainage.
- Your drainage still matters most. Whatever happens on the public side, roof water, irrigation and leaks on your own lot are the factors you control.
A short list for owners near the bluffs
- Keep a dated baseline of the house: cracks, door fit, floor slope, and any gaps opening on the ocean-facing side.
- Walk your drainage after the first big storm each winter. Look for water ponding near the house or running toward the bluff.
- Keep geotechnical reports, surveys and permits together, and know who prepared them.
- If you are away for long stretches, arrange for someone to check the property after major storms.
- Expect any work near the edge to involve Design Review and coastal permitting, with timing that depends on the agencies. No one can promise you an outcome or a date.
Our role
We work on the house and the structures that support it: foundations, framing, drainage, and bluff or seawall work where an engineered design and the required approvals are in place. We do not judge whether a bluff is stable; that is for your engineering geologist and geotechnical engineer, and we coordinate with licensed engineers as needed.
If you would like a careful look at a home on or near the bluffs, request a Free Quote. Further reading on our site: bluff and hillside homes, bluff and seawall stabilization, Design Review for foundation projects and structural monitoring for second homes. Our companion entry turns to the beach-level side of town: North Beach cottages and FEMA’s 50 percent rule.