COUNTING BIRDS:
Regulatory Foundations & Proof of Life
As we mentioned in the previous chapter, the loss of the San Francisco Bay would have been detrimental. Specifically, it would have caused the destruction of:
1. Wildlife habitats and the food chain: San Francisco Bay’s wetlands and shallow waters provide feeding, nesting, and nursery habitat for fish, shorebirds, waterfowl, and migratory birds along the Pacific Flyway. They also support the small organisms at the bottom of the food chain, which sustain larger fish and birds. The Bay is especially important as a nursery for species such as salmon, halibut, striped bass, and other fish. The remaining salt marshes also support threatened and endangered species, so filling the Bay would have removed habitat that entire ecological communities depend on.
2. Natural water purification: Wetlands act like a living filter. They absorb or trap pollutants, nutrients, and sediment carried by urban and agricultural runoff before those materials reach open Bay water. The Bay had already been heavily polluted by sewage, industrial waste, garbage dumps, and runoff. Filling more wetlands would have reduced the natural system’s ability to process pollution and would have concentrated contamination in a smaller remaining waterway.
3. Flood and shoreline protection: Wetlands slow stormwater, trap sediment, and reduce shoreline erosion. They function as a protective buffer between the Bay and nearby communities. This is especially important today because much of the former Bay shoreline is low-lying and developed. A narrow, hardened channel would likely provide less room for water and sediment to spread safely during storms and rising sea levels. Ironically, the very wetlands that some developers viewed as “unused land” can reduce the need for expensive engineered flood-control structures
Save the Bay's technical role in the South Bay Salt Pond Restoration Project (SBSPRP) is narrow, serving only as a donor, but its own Habitat Restoration Team is a runs volunteer revegetation at SBSPRP sites, such as conducting transition-zone planting near the Ravenswood levee breach. Furthermore, when 1,433 acres of the Cargill tract that were originally excluded from the sale were proposed for housing instead, Save the Bay led the public advocacy campaign against it.
Meanwhile, fully restoration projects like SBSPRP typically proceed under streamlined federal wetland permits. When they began, the stakes were high:
The salt marsh harvest mouse and the California clapper rail (including rideway rails) were both listed as federally and state Endangered in 1970. This is still serious — as of 2021, an estimated 1,400 Ridgway's rails existed Bay-wide against a 5,400-bird recovery target
The California least tern was listed federally Endangered in 1970. They breed largely on abandoned salt flats and levees.
The western snowy plover, federally listed as Threatened, nests on dry salt-pond bottoms that now hold roughly 10% of the entire Pacific Coast plover population.
The results are measurable. 3,770 acres of tidal marsh have been restored to date, alongside 8.4 miles of completed public trail. Western snowy plover fledglings climbed from a low of 72 birds in 2003 to 383 in 2025, which is about three-quarters of the way to the federal recovery threshold. And overwintering waterbird counts within the restoration footprint more than doubled between 2002 and 2014 — while on ponds Cargill kept in active salt production over that same stretch of time, the count barely moved.
In 2003, Cargill Inc. sold 16,500 acres of its salt pond holdings — 15,100 of them in the South Bay — for $100 million, brokered by Senator Dianne Feinstein and purchased jointly by the U.S. Fish and Wildlife Service, California's Department of Fish and Game, and the State Coastal Conservancy. This was significant because, previously, the ponds were privately operated for salt production and industrial purposes. After the acquisition, restoration partners could make decisions about engineering and hydrologic modelling, management of salinity and water levels, and monitoring how birds, fish, plants, and sediment responded (NASA). While Save the Bay was not a party to that sale, the anti-fill regulatory culture it created is what made a hundred-million-dollar deal to convert industrial salt ponds back into public wetland politically feasible at all — recall how, in the era Save the Bay organised against, filling was progress, not something you paid to reverse.
As mentioned in our last chapter, the regulatory foundation that would later come to protect wetlands began with the McAteer-Petris Act, which created BCDC, and with it, a legal precedent that the Bay's wetlands were worth protecting. Decades later, that precedent became the political groundwork for the largest wetland reacquisition in the Bay's history.
INTERLUDE: REGULATORY BACKGROUND
SALT PONDS AND SURE PROOFS
I decided to look at a larger organisation, which Save the Bay is a member of: The South Bay Salt Pond Restoration Project (SBSPRP), a collaborative nonprofit that aims to restore 15,100 acres of former industrial salt ponds. I used two datasets from SBSPRP and United States Geological Survey (USGS) to hopefully demonstrate an increase in bird population in relationship with SBSPRP’s restoration efforts.
It’s important to note that "protected" doesn't automatically mean "working." You could technically fence off a chunk of land, call it conserved, and it could still be a dead zone if nothing's living there. A 2022 review of Philippine marine reserves, for example, found that “while the government depends on its MPA [marine protected area] system in protecting its seascapes and meeting its international commitments, research results suggest that only a third of the country’s MPAs are well-managed and only around 1 % of the country’s coral reefs is protected” (Chavez). They were referred to as “dummy parks”—legally designated but lacking sufficient monitoring and enforcement, with problems including illegal fishing, insufficient funding, and lack of monitoring and evaluation.
Whether a location is truly protected can only be confirmed with time and continued monitoring. Thankfully, SF Bay's wetlands do exactly that with decades of follow-up that we can reference.
The South Bay Salt Pond Restoration Project
The largest tidal wetland restoration project on the West Coast. When complete, the restoration will convert 15,100 acres of commercial salt ponds at the south end of San Francisco Bay to a mix of tidal marsh, mudflat and other wetland habitats. The goal is to restore and enhance wetland habitats to provide wildlife-oriented public access and recreation, and to provide for flood management in the South Bay. They expect that restoration will benefit a greater diversity of wildlife, particularly endangered species.
Waterbird Nest Abundance in South San Francisco Bay (Ackerman, Hartman, and Herzog, 2025)
This open-source dataset covered nest counts of American avocets, black-necked stilts, and Forster’s terns by year and by pond/site. It was generated from yearly nest monitoring surveys within wetlands in south San Francisco Bay, particularly on the Don Edwards San Francisco Bay National Wildlife Refuge and the Eden Landing Ecological Reserve.
The raw data from USGS separated counts by site. To see how nesting activity shifted over time, I summed the nest counts across all monitored sites within a given year, ending up with one number per species per year. The original data can be by clicking the "Waterbird Nest Abundance in South San Francisco Bay" box above.
Note:
for site-years with "." nests, researchers are confident there were not large numbers of nests at that site in that year; however, it is possible that a few nests may have been active briefly and missed because limited staff necessitated not monitoring all potential nesting sites each year. They were treated as “0” for the aggregation, as the documentation says these represent " not large numbers".
2020, 2021, and 2023 had no survey data collected at all
Unfortunately, it's not a clean success story. While Forster's terns are doing great, American avocets and black-necked stilts are near twenty-year lows over that same period. A 2021 study by Hartman et al attributed these declines to the loss of salt-pond island nesting habitat as ponds are being converted to tidal marshes, compounded by a growing population of predatory California Gulls. Unfortunately, newly engineered nesting islands in remaining ponds did not seem to fully offset the losses. SBSPRP chose to make this trade-off because the tidal marshes will benefit a greater diversity of species, including the California clapper rail, the salt marsh harvest mouse and several fish and aquatic species that were not included in this dataset. Meanwhile, American avocets and black-necked stilts are a bit more durable, thriving even in sewage treatment lagoons.
Uncomfortable tradeoffs like this are not uncommon. A 2026 Bay Nature feature describes a related, ongoing issue: western snowy plovers are being crowded onto fewer remaining salt ponds as SBSPRP continues breaching dikes, forcing project managers to deliberately keep some ponds dry. Dave Halsing, the salt pond restoration’s director, calls it a “very complicated balancing act.” SBSPRP is trying their best to maintain both populations because, according to Katie Smith, a salt marsh harvest mouse expert, making sure there’s “higher diversity [of restoration] may provide greater resilience” to all species, especially as sea levels reshape coastal areas in unpredictable ways. Despite their efforts, it doesn’t change the fact that “each new marsh is…one less place a plover can breed.”
In short, it is very difficult for organisations like SBSPRP to eat both halves of their cake, as it were. Realistically, a functioning ecosystem won’t show every species climbing neatly upwards. Real habitats have trade-offs, population cycles, winners and losers. An actually alive ecosystem produces messy outcomes, but that’s also what makes it so frustrating. As science director Maddy Schwarz puts it, “When something goes wrong, it’s really hard to tell what is going wrong. And when something is going right, it’s really hard to tell what’s going right.” It is important to keep this in mind while observing similar environmental outcome reports. An obvious happy outcome is not always guaranteed; less-then-ideal data shouldn’t be written off as an automatic failure.
