If you walk the Old Rail Trail loop at Blackie's Pasture on a regular basis, you've probably already noticed something different this month. Machinery is back along the shoreline near Greenwood Beach, the same stretch that saw crews moving rock and soil back in March. This time it's not a quick visit. What's starting now is the main construction push on a shoreline restoration that's been years in the making, and it happens to land in the same few weeks as two other things that show up on this same loop every fall. None of the three are related to each other in cause, but all three are converging on the same half-mile of shoreline, and if you use this trail the way most Tiburon residents do, it's worth knowing which is which.
The Machinery Is Back Because This Is the Real Build
The project is called the Greenwood Beach Restoration Project, and it's been moving through phases for a while now. Marin County and the Town of Tiburon spent 2025 finishing environmental review and permitting, with Audubon California working alongside them as a restoration partner. In November 2025, the team built a small pilot version of a new kind of shoreline structure called a drift-sill, just to see how it would hold up over a winter of storms before committing to the full design. That pilot sill got monitored through the rainy season. Then in March 2026, Tiburon crews built the actual sediment retention drift-sill along the beach, the phase that had you dodging orange fencing near the parking area.
September is the big one. Construction of the remainder of the project, the part that reshapes roughly 1.4 acres of shoreline at Greenwood and Brunini beaches, is scheduled to run four to six weeks. If it started in early September, that puts substantial completion somewhere in the second half of October, weather and permitting allowing. The work is funded by a $1.4 million grant from the State Coastal Conservancy, awarded to the Town of Tiburon in fall 2024 specifically to finalize the design and build it. If you have questions about access or timing while you're out there, the Town's public works engineering manager, David Eshoo, has been the point of contact on this project since the early phases.
What Was Actually Wrong With the Beach
It's worth understanding why the county is spending real money and multiple construction seasons on a strip of shoreline that most people just jog past. Greenwood Beach used to be a wider barrier beach that sheltered a non-tidal salt marsh with shallow seasonal ponds. Over the decades, as the shoreline eroded, people dumped in asphalt, concrete rubble, and sand to try to hold the line against wave action. It didn't work. The fill kept scattering across the adjacent mudflats instead of staying put, leaving a shoreline that's now described in county planning documents as hazardous to walk near and poor habitat for the shorebirds the bay is supposed to support.
The fix is a genuine departure from how this kind of erosion usually gets handled. Instead of another layer of rip-rap, the design calls for a living shoreline: regraded slopes stabilized with native beach vegetation, large woody debris, and those cobble salt-marsh drift-sills running perpendicular to the shore to trap sediment the way a natural barrier beach would. It's a nature-based approach that Audubon and the county are treating as something of a demonstration project, one that could inform how other eroding stretches of Richardson Bay get handled down the line. That's part of why the timeline has been so deliberate. A pilot sill, a winter of monitoring, then the full build, rather than a quick rip-rap patch job.
Two More Things Land on the Same Stretch This Fall
Here's where it gets interesting for anyone whose daily walk runs through this exact footprint. Two other things happen at Blackie's Pasture every fall, on their own fixed schedules, completely unrelated to the construction calendar.
- October 1 through March 31: the Richardson Bay boat closure. Every winter, the Richardson Bay Audubon Center and Sanctuary closes its 900 acres of open water to all boat traffic, including kayaks, canoes, and paddleboards. This isn't new and it isn't related to the construction. It's mandated by a Richardson Bay Regional Agency ordinance and exists to protect the tens of thousands of migratory ducks, geese, and shorebirds that use the bay to refuel or overwinter. The closure area is marked by buoys and pilings and runs from the edge of the Cove housing complex south of the Sanctuary north to Blackie's Pasture. If you're on foot or on a bike, this doesn't affect you. The historic Richardson Bay Rail Trail itself stays open year-round, and leashed pets are allowed on it even during the closure.
- The Run4Reed fun run, an October fixture. The Foundation for Reed Schools holds its annual fundraising run at Blackie's Pasture, with courses that use a portion of the Old Rail Trail past McKegney Green, circle south of Knoll Park, and return to Blackie's Pasture for a post-run gathering with food trucks. Last year's run landed on Friday, October 10. It's an annual event on its own calendar, not tied to the restoration schedule, so watch the Town's calendar for this year's exact date. If construction is still active when it lands, runners and regulars will be sharing trail space with equipment and fencing that day.
None of these three things caused each other. The construction is on a grant-funded, weather-dependent build schedule. The boat closure happens every single year on the same calendar dates regardless of anything else going on. The fun run is an annual school fundraiser that's been landing on this same course for years. But because they all touch the same quarter-mile of shoreline, this particular September and October will feel busier out there than most, and it helps to know why before you assume it's all one thing.
What This Actually Means for Your Loop
If Blackie's Pasture is part of your routine, here's the practical read. Expect active construction through late September and likely into October, with equipment, fencing, and possibly some rerouting near the Greenwood Beach section specifically. The rest of the Old Rail Trail, including the stretch past McKegney Green and around Knoll Park, should remain accessible the way it always has. If you paddle or kayak in the bay itself, that's off the table starting October 1 regardless of how the construction is progressing, and it stays off the table through the end of March. If Run4Reed lands on the same kind of date it did last year, expect runners on part of your usual route that morning and a livelier scene at the pasture itself once the run wraps.
The bigger picture is that this fall is the busiest this shoreline is likely to be for a while. Once the main build wraps, probably sometime in October, the drift-sills and new beach material will need time to settle and the native vegetation time to establish. Audubon's restoration team has been growing plants specifically for this project in their nursery, work that started well before this month's construction. That's a multi-year process, not something that finishes the day the equipment leaves. So the disruption you're seeing right now is genuinely the busiest phase, not a preview of something ongoing.
Blackie's Pasture has been a fixture of daily life in Tiburon for a long time, the kind of place where regulars notice when something's different before they know why. This fall, three separate things happen to be different at once. Knowing which is temporary construction, which is an annual wildlife closure, and which is a one-day community event makes the next few weeks a lot easier to plan around.
If you're weighing a move in or around Tiburon and want a read on how neighborhood details like this factor into timing a purchase or sale, Carla Giustino has spent more than 25 years tracking the details that don't show up in a listing description. Request a complimentary Marin market consultation to talk through what's actually happening on the ground in the neighborhood you're watching.
