Drive past the San Elijo Lagoon Nature Center on Manchester Avenue some late-winter morning and you might see an excavator parked in the mud, moving sand where water used to be. If you remember the ribbon-cutting back in 2022, when officials called the lagoon's restoration complete, the machinery looks like a step backward. Wasn't this supposed to be finished?
It was finished. It's also supposed to keep needing this. That contradiction is the most interesting thing happening in Cardiff-by-the-Sea's backyard right now, and almost nobody who lives here has had it explained.
What "Complete" Actually Meant in 2022
The San Elijo Lagoon Restoration Project ran from late 2017 to 2022, funded by $120 million from San Diego's half-cent TransNet tax rather than donations. It widened the tidal channels, dredged new mudflats across the reserve's east, central, and west basins, and replaced the aging Interstate 5 bridge with a longer, wider span built specifically to let more seawater move through the lagoon on every tide.
The results were real. Before the project, biologists had recorded a single patch of eelgrass in the lagoon. By the June 2022 ribbon-cutting, Nature Collective counted roughly 150 patches, along with the first octopus observed in the lagoon's channels in more than three decades of monitoring and five fish species never documented there before. Endangered Belding's Savannah Sparrows, Ridgway's Rails, and California Least Terns turned up in the restored marsh. Doug Gibson, the nonprofit's executive director and principal scientist, described the newly widened main channels simply: "Think of the main tidal channels as the lungs of the lagoon."
The same construction also built the pedestrian suspension bridge that now hangs beneath the I-5 overpass at Manchester Avenue, connecting the Nature Center Loop Trail to the Pole Trail on the other side. That bridge turned what used to be an out-and-back nature walk into a three-mile loop that links Cardiff to Solana Beach, part of a longer bike and pedestrian corridor running from Solana Hills up through new paths along Manchester and Birmingham Drives.
By every measure the project set for itself, it worked. So why is there an excavator back at the same spot four years later?
Then the Inlet Closed Again Anyway
In January 2025, Nature Collective announced it had secured most of a $2.7 million SANDAG grant to dredge the lagoon's main channel and inlet, where sand had built up badly enough to trap water behind the Coast Highway 101 bridge and cause flooding during a run of King Tides. The money was earmarked specifically as "adaptive management" for the restoration project, not as a separate repair. A contractor called Pacific Dredge and Construction spent eight to ten weeks starting February 14, 2025, pulling sand from the channel east of the Coast Highway bridge and depositing it on Cardiff State Beach.
A year later, it happened again. Nature Collective's March 2026 update on the reserve describes the inlet closing once more, even after a February storm generated enough flow to punch open a temporary natural breach. That breach didn't hold. Crews scheduled a fresh land-based excavation starting March 19, 2026, working west of the railroad bridge this time, with the removed sand going toward rebuilding part of the Cardiff Living Shoreline dunes just south of the Charthouse Restaurant.
Two dredging events in two years, on a lagoon whose restoration was declared finished in 2022. That's not a project running behind schedule. That's the schedule.
Why a Finished Project Needs a Yearly Redo
The mechanism is straightforward once you see it. Sand moves constantly along this stretch of coast, drifting south from beaches north of the lagoon and settling wherever the water slows down, which is exactly what happens at a narrow inlet squeezed between Coast Highway 101 and the railroad tracks. No amount of channel-widening changes the fact that this is still a lagoon mouth in a heavily built environment, hemmed in by infrastructure that didn't exist when the tidal system first formed. Left alone, sand piles up at the mouth until the inlet closes, water backs up into the marsh, and oxygen levels start to drop.
That last part isn't hypothetical. Before the restoration, Nature Collective's data showed that a fully closed inlet would drop to insufficient oxygen levels within about a week, a number stark enough to justify redesigning the whole system in the first place. Closure still carries that risk today, restoration or not, which is exactly why the nonprofit doesn't wait for a storm to reopen the mouth on its own. The March 2026 dig was also timed deliberately for the start of bird nesting season, so water levels drop before the endangered Ridgway's Rail and Belding's Savannah Sparrow need dry cordgrass to nest in.
Read that way, the $2.7 million adaptive management grant isn't a sign the 2022 project fell short. It's the maintenance budget the project always assumed it would need, written into the plan rather than discovered as a surprise. A wetland squeezed against a freeway and a highway bridge doesn't get to run on autopilot. It gets managed, on a schedule, indefinitely.
What This Actually Means for a Walk Through the Reserve
None of this is abstract if you're the one walking the loop. A few specifics worth knowing before your next visit:
- The three-mile loop still works during dredging. Past excavations have focused on the channel and inlet near the Nature Center and Coast Highway 101, not the suspension bridge trail itself, though closures do happen for repairs and weather. Check Nature Collective's site before a visit if you're planning to cross the bridge.
- The sand under your feet at Cardiff State Beach has a backstory. Much of what gets dredged from the lagoon channel is pumped straight onto the beach and the Living Shoreline dunes near the Charthouse. That's not imported sand. It's the same sand that closed the inlet, redeployed.
- Eelgrass is the easiest thing to check for yourself. Look into the main channel from either pedestrian bridge near the Nature Center. A count that went from one patch to roughly 150 after the 2022 restoration is the kind of number you can actually verify with your own eyes on a low-tide morning.
- Wings Over Wetlands marks the other end of the cycle. Nature Collective's free January festival, held most recently on January 24, 2026, celebrates the migratory birds that use the lagoon each winter, right before nesting season begins and the spring dredging work gets scheduled around it.
The Takeaway for Anyone Who Lives Near It
The easy story about San Elijo Lagoon is the one told at ribbon-cuttings: a $120 million restoration, finished, with the numbers to prove it worked. The truer story is that finishing a restoration this close to a freeway and a highway means signing up for permanent, funded, recurring intervention. Cardiff didn't get a monument. It got a working system that needs a person with a shovel or an excavator to check in on it every year, usually right around late winter, usually for a few weeks, usually right before the birds start nesting.
That's a strange thing to be proud of, but it's a better outcome than the alternative. A lagoon that never needed maintenance again would probably also be a lagoon nobody was watching closely enough to notice.
If you're the kind of person who wants to understand how a place actually works before deciding what living near it is worth, that's the conversation Stacy Smith has with clients across Cardiff, Encinitas, and the rest of coastal North County every day. Let's Connect.
