September at the Palo Alto Baylands: A New Levee Beneath Two Old Traditions

Anyone who walks the Baylands loop on a weekday morning has the route memorized by now. Past the Duck Pond, along the chain-link edge of the airport, out to where the boardwalk opens onto the marsh and the Dumbarton Bridge sits low on the horizon. This September, a stretch of that path looks different. Along the bank near the wastewater treatment plant, a slope of new plantings, black elderberry, ninebark, and marsh baccharis, has replaced what used to be bare levee wall. It isn't ornamental landscaping. It's the Bay Area's first horizontal levee, and it opened to the public on September 10.

The rest of the month's calendar looks almost exactly like it has for years. Palo Alto Airport Day returns on September 20 the way it has for a long stretch of Septembers before it. The Moonlight Run marks its 42nd year on September 25. Both are Baylands fixtures that longtime residents could probably describe from memory. But the shoreline underneath both events changed first, and most of what's now visible from the trail wasn't there for last year's race or last year's open house.

The Bay's First Living Levee

The Horizontal Levee Pilot Project sits directly across from the Regional Water Quality Control Plant, the facility that treats 20 million gallons of wastewater a day for more than 230,000 residents and businesses across Palo Alto, East Palo Alto, Los Altos, and Mountain View. In 2024 the plant began at least $369 million in upgrades designed to strip enough nitrogen from its treated water that it can be released into local waters without feeding the algal blooms that have hurt marine life elsewhere in the Bay.

The levee is where that upgrade becomes visible. Recycled water from the plant now irrigates the new plantings, and the freshwater it creates forms a transitional habitat between upland and tidal marsh, the kind of zone that species like clapper rails, black rails, the western pygmy blue butterfly, mud crabs, and various fish use for foraging, nesting, and shelter from high tides. Construction started in September 2025, a partnership between the city of Palo Alto, the consulting firm Environmental Science Associates, the San Francisco Estuary Partnership, Save the Bay, and researchers from the U.S. Geological Survey, Cal State Channel Islands, and UC Davis. Save the Bay ran volunteer planting days last year that drew people from across the region to put the elderberry and baccharis into the ground by hand.

Heidi Nutters, assistant director of the San Francisco Estuary Partnership, put it simply at the opening.

"Projects like this allow us to reimagine our wetlands for people and for nature."

Mayor Vicki Veenker connected the project to the city's broader sustainability goals, noting it helps reduce Palo Alto's carbon footprint while improving the quality of the recycled water flowing through the preserve. For a piece of infrastructure that most visitors will walk past without a second look, it represents years of coordination between a city utility, a state agency, a national nonprofit, and three research universities.

The Same Runway, Fifteen Days Later

Palo Alto Airport Day returns on September 20, from 10 a.m. to 2 p.m., with free cockpit tours and formation flight demonstrations overhead. The event gives residents a close look at an airfield most only see from the Baylands trail or a passing car on Embarcadero Road. The airport itself covers 102 acres bounded by San Francisco Bay and the Baylands Nature Preserve, with a single 2,443-by-70-foot asphalt runway, a small footprint for a facility that handles roughly 155,000 flight operations a year, among the busiest general aviation airports in the Bay Area.

The city took over operations from Santa Clara County in 2014, and the open house has become one of the more reliable ways for non-pilots to get inside the gates. The 2024 event, held that September 29, drew more than 5,000 visitors according to the Palo Alto Airport Association's own count, with air traffic control tower tours and access to a Stanford Life Flight helicopter among the draws. Organizers this year are recommending visitors arrive on two wheels rather than by car, with a free bicycle corral staffed by volunteers from the Silicon Valley Bicycle Coalition, since the trails along the Baylands offer a view of incoming aircraft that the parking lot doesn't.

The airfield's tight quarters next to sensitive wetlands have drawn attention before, including after a small plane incident in February 2025. Federal grant assurances currently prevent the city from unilaterally banning leaded aviation fuel or restricting flight hours, a constraint that has shaped an ongoing Long Range Facilities and Sustainability Plan the city started working through this year. None of that changes what Airport Day is on the ground: a family event on a runway most residents never get to stand on, happening ten days after the wetland beside it got its first new piece of shoreline in years.

A 42-Year Tradition Skips Its Longest Race

Five days after Airport Day, the Palo Alto Weekly Moonlight Run and Walk marks its 42nd anniversary on September 25, under a full moon at the Baylands. The race has offered a 5K walk, 5K run, and 10K run for decades, a benefit event for local nonprofits presented by the city. This year, for the first time in recent memory, there's no half marathon option. Organizers cited construction along the usual route and said the longer distance will return in 2027 once that work wraps up.

The race has always been a fixture of the Baylands calendar regardless of what else is happening at the preserve that month. What's different this year is the backdrop. Runners circling the marsh under the September moon will pass within view of plantings that didn't exist for the 41st running, part of a shoreline that's now doing measurable ecological work rather than just holding back the Bay.

Same Three Weeks, Different Shoreline

Airport Day and the Moonlight Run will look, on the surface, like they always have. Families will climb into cockpits. Runners will cross the same finish line they've crossed for decades, just without the half marathon this time. But both events now share their three-week stretch of September with a project that took a year of construction, a multi-agency partnership, and $369 million in treatment plant upgrades to make possible. The Baylands didn't get a new calendar this month. It got a new piece of ground under the old one.

If you spend time on that loop yourself, whether it's the Tuesday morning walk, Airport Day with the kids, or the Moonlight Run under a full moon, Kathleen Pasin would genuinely like to hear what you notice out there this fall. She walks those same trails often enough to know when something's changed.