Shoreline's Newest Marsh Is Having Its First Winter, and the Trail Out to It Is Closed for Repairs

"We should take great pleasure as time goes on, watching it develop into a marsh," Mountain View City Council member Pat Showalter told the crowd on Feb. 20, according to the Mountain View Voice. She was speaking at the edge of Pond A2W, the 435-acre former salt pond just north of Shoreline Park.

Eight months later, the trail built so people could watch that happen is behind a closure sign. Crews are hauling dirt and rock back onto the levees under it. A second pond next door has started its own construction. This is the first winter A2W has spent open to the tides. For anyone who walks, runs or birds at Shoreline, the bay edge is now a marsh you can watch as it forms, surrounded by crews still maintaining and expanding it. Where you can stand to see it this season depends on where those crews are working.

A Pond That Was Opened to the Tides in January

Construction at A2W ended in late January 2026, and the cost is estimated at about $20 million, the Mountain View Voice reported. The work repaired eroding levees, built five habitat islands and added 1.2 miles of public trail.

The background explains why the pond took so long. The federal government paid $100 million in 2003 to buy 15,100 acres of salt ponds around the Bay from Cargill Salt, according to Palo Alto Online. Before work on A2W could start, it took about three years to collect the 180,000 cubic yards of dirt the project needed, most of it from local construction sites. Dave Halsing, executive project manager of the South Bay Salt Pond Restoration Project, called A2W "one of the harder ones," because the pond held 2 to 5 feet of water for the whole build.

On the pond's east side, crews built a roughly one-mile extension of the Stevens Creek Trail on top of the levee that separates the pond from Stevens Creek. That levee was deliberately breached so Bay water could come in. Two armored bridges carry the trail over the breaches out to a lookout on the Bay. The west side, with its five islands, was designed for wildlife only and is closed to the public. Save The Bay's description of the site says the levees were breached in January 2026, which restored tidal flow to the pond.

Halsing summed up what happens next in five words that Palo Alto Online quoted: "Nature (will) do the actual restoration."

Eight Months Later, Crews Are Back on the Levees

The engineered edge still needs work while nature does its part. The City of Mountain View's trail page says crews are placing earthen fill and riprap rock to repair erosion damage on the pond-side faces of A2W's eastern and northern levees. Those are the levees under the Song Sparrow Spur Trail. The City says the repair will keep the new trail in place and keep access open for Refuge staff, authorized researchers and PG&E crews.

The two agencies give slightly different dates. The City lists September through November 2026. The South Bay Salt Pond Restoration Project lists Aug. 31 through the end of November 2026. Both describe the levees as damaged by erosion. The Restoration Project says the spur will reopen "this fall" once the repairs are finished.

The closure affects regular trail users in two ways:

• The Song Sparrow Spur Trail stays closed for the whole construction period.
• The northernmost end of the Stevens Creek Trail, south of the gate onto the spur, closes for shorter stretches when materials arrive.
• No detour is posted. Both are out-and-back trails, and the closures sit north of the last trail junction.
• Trucks come in by road. They drive along Amphitheatre Parkway, N. Shoreline Boulevard and Crittenden Lane, then onto Shoreline Park service roads and up the Stevens Creek Trail.

A2W's own construction also included repairs. Before it ended, crews removed a defunct water-control tower from the north levee and plugged the hole it left, according to Palo Alto Online.

The Next Pond Has Already Started

West of A2W, the Restoration Project has begun work on Pond A1. This 275-acre former salt pond north of Shoreline Park and east of Charleston Slough will be restored to tidal marsh, with a new public trail and a viewing platform. The project's April 14, 2026 announcement put A1 construction in late 2026 or 2027. It expects construction to finish in 2028, with monitoring after that.

In this first phase, the contractor is building a temporary access ramp at the northern end of Shoreline Park, next to the Bay Trail. Trucks take San Antonio Road to Terminal Boulevard, then drive into the park on paved trails. Short closures happen on weekdays between 7:30 a.m. and 4 p.m., including on part of the Bay Trail, with flaggers on site. The City says most Shoreline trails stay open when no hauling is underway.

A third, smaller project rounds out the season. Phase 1 of the City's Shoreline Park Water Control Structures Improvements, listed as Project 23-44, closed the Saling Lake Boardwalk from Oct. 27 to 30. The City notes that the schedule could change.

Weekends and evenings have no hauling. Weekdays have the trucks. Shoreline itself is open 6:30 a.m. to 30 minutes after sundown, seven days a week, so the evening window shrinks as November days get shorter.

How Long Until It Looks Like a Marsh

People who were there in February heard two different timelines. Chris Barr, acting complex manager for the San Francisco Bay National Wildlife Refuge, told the Mountain View Voice that in less than a decade the pond will be a "full, vibrant marsh on the edge of the Bay." A month earlier, Palo Alto Online described the process as tides carrying sediment into the pond and plants taking hold "over the next few decades."

The mechanism is the same in both accounts. Each tide brings in sediment and seeds that settle on the pond floor. On the south edge, the sloped habitat zone that protects the levee of the closed landfill under Shoreline Park has its own caretaker. Palo Alto Online reported that Save The Bay would spend the year tending it, using gumplant and salt grass raised in its Peninsula nurseries.

That slope runs beside the paved Bay Trail. Save The Bay's planting site is about a half-mile, 10-minute walk from the Shoreline Golf Links parking lot at 2940 N. Shoreline Blvd. Volunteer dates and their current status are posted on Save The Bay's events page.

The habitat islands also change roles over time. For now, Halsing said, birds will likely use them for nesting and roosting. As the marsh fills in, they become places where land animals can shelter during high tides.

Timing a Walk This Winter

The tides, the birds and the A1 truck schedule all affect when it's worth going out. These are the dates that matter from here through January:

1. Saturday, Nov. 7, 8:30 to 11 a.m. The Santa Clara Valley Bird Alliance leads a 1.5-mile field trip covering Charleston Slough, Coast-Casey Forebay, Salt Pond A1 and Shoreline Lake. It meets near Terminal Boulevard and San Antonio Road. That's the weekday truck route, but there's no hauling on a Saturday.
2. Wednesday, Nov. 11. No tours at Rengstorff House.
3. Saturday, Nov. 14, 8:30 to 11 a.m. "Drop-in: Fall Migration at the Bay!" puts docents on the Charleston Slough observation deck to help identify birds. See the Bird Alliance listing.
4. Nov. 24 to 26. The first statewide King Tides of the season, according to the California Coastal Commission. This is A2W's first full winter as a tidal pond.
5. Dec. 23 to 25. The second King Tide series. The Commission notes that Northern California locations may also see one on Dec. 22.
6. Dec. 24 through Jan. 3. Rengstorff House tours pause. The grounds stay open dawn to dusk unless the house is rented.
7. Jan. 21 to 22, 2027. The last statewide King Tides of the season, with Jan. 20 or Jan. 23 also possible locally.

Outside those dates, free Rengstorff House tours run Tuesdays and Wednesdays from 1 to 4 p.m. and Saturdays from 9 a.m. to noon.

Shoreline's burrowing owls are a separate count from the marsh. The City's 2026 owl table recorded 8 owls in September, seen in the Northeast Meadowlands and on the golf course's Back 9. Over the previous five years, November and December each averaged 16. That's a historical average, not a forecast for this year. The City asks visitors to stay on the paths and watch owls from a distance.

On the lake side, Shoreline Lake lists its Bistro as temporarily closed for remodeling. The Boathouse is open with espresso, snacks and patio seating. Boathouse rentals include kayaks, rowboats, pedalboats, sailboats, stand-up paddleboards and bicycles. At Shoreline Golf Links, the driving range is open 7 a.m. to 8 p.m. every day except Wednesday, when it opens at 11 a.m. The last balls are sold at 7 p.m.

When the Song Sparrow Spur reopens, the lookout at its far end will give you the same view the February crowd had, with almost a year of tides added. The City's trail status page will show when it changes from "Alert" back to "Open."

Restoration at A2W and A1 is changing North Bayshore. If you'd like to know how that fits with your own plans in Mountain View, Wendy Kandasamy offers a complimentary market consultation and home valuation, grounded in local detail like this.