For more than a century, commercial and residential development has been consuming the wetlands, tidal flats and beaches surrounding San Francisco Bay, the largest and most biologically rich estuary on the West Coast. Now, those same development forces may help reverse the trend, making possible the restoration of thousands of acres of critical wildlife habitat. Although one would assume that environmentalists welcome the change, the prospect has not been embraced wholeheartedly by the Bay Area's green community. That is because the deal involves commercial tradeoffs, an increasingly common conservation tactic as property values rise and pressure to develop open space increases in California. To obtain the land and raise the money needed to restore it, conservationists often must accept commercial projects they might otherwise oppose. It is a choice between pragmatism and ideological purity. The most significant restoration proposals affecting the Bay grow out of a desire to expand two of the area's most critical transportation hubs: San Francisco International Airport and the Port of Oakland. The airport is notorious for chronic flight delays caused by bad weather. Its four parallel runways are separated from each other by only 750 feet; the Federal Aviation Administration requires 4,300 feet between simultaneously landing planes when visibility is impaired. Consequently, fog or clouds force the airport to shut down two of the runways. The resulting delays have given SFO the worst on-time record of any major U.S. airport and send ripples throughout the nation's air traffic system. The situation is a civic embarrassment for San Francisco, and the congestion and delays have profound economic consequences. Forty million airport visitors contribute $10.7 billion to the local economy each year, and the products of Silicon Valley's high-tech manufacturing establishment increasingly rely on air transport to reach global markets. Passenger traffic is projected to increase to 51 million a year during the next five years. Airport officials have proposed replacing two of the runways, building the new ones a mile farther into the bay. That would require filling nearly two square miles of the bay. A few decades ago, this would not have been difficult to accomplish. According to the Audubon Society, the area of open water at high tide downstream from the Sacramento-San Joaquin River Delta has decreased since the Gold Rush era from 516,000 acres to 327,000 acres. Of the original 23 miles of sandy beaches ringing the bay, only seven remain. Tidal marsh has decreased from 190,000 acres to 40,000 acres, and 50,000 acres of tidal mudflats have dwindled to 29,000. Altogether, 137,000 acres of baylands (the area between the lines of high and low tide) have been diked and 50,000 acres have been filled. The consequences of shrinking the bay have been profound for the creatures that rely on these rich, energetic biological systems. About 500 species of fish and wildlife call the baylands home, and 20 of them are listed as threatened or endangered. Concern about continuing encroachment into the bay led in 1968 to the state Legislature's creation of the San Francisco Bay Conservation and Development Commission (BCDC). The commission was given the authority to approve or deny proposals to fill the bay. While it has occasionally approved small projects, the commission has generally required builders to offset each acre of fill with two acres of restored habitat elsewhere. Filling two square miles of the bay for runway construction poses a substantial mitigation challenge. And Bay Area environmental groups have been extremely critical of the proposal. Looking for a restoration opportunity big enough to satisfy their critics, airport officials found their eyes drawn to a vast complex of salt-production ponds along the south end of the bay in San Mateo, Santa Clara and Alameda counties. Acquired by Cargill Inc. in 1975 when it purchased the Leslie Salt Co., the 19,000 acres of ponds were once part of the bay, but were diked off from it more than a century ago. In 1999, Cargill began negotiating with state and federal agencies to sell the ponds for restoration as wildlife habitat. The asking price: $300 million, which would make it the second-largest state-federal land acquisition in California history (the Headwaters Forest deal, at $480 million, was larger). Negotiations picked up speed last year when San Francisco officials hit on the idea of using the state-federal purchase of Cargill's ponds as leverage for airport mitigation. (See CP&DR September 2000, CP&DR Economic Development, January 1999.) With the help of Mayor Willie Brown, the former Assembly speaker, they persuaded the Legislature to approve and Gov. Gray Davis to sign a bill authorizing $25 million in state funds for the purchase. Last October, the federal government agreed to chip in $8 million from the Land and Water Conservation Fund. Airport officials have said they have $200 million to spend on the restoration, and more state money could be authorized this year. A similar commercial tradeoff is in the works related to expansion of the Port of Oakland. The nation's fourth-busiest commercial harbor plans to dredge 13 million cubic yards of sediment from the shipping channel, deepening it to 50 feet and allowing it to handle larger container ships. In December, the port won approval from the BCDC to deposit 1 million cubic yards as a base for dockside construction, pump 7 million cubic yards into the Middle Harbor area to create 200 acres of shallow eelgrass habitat, and send 5 million cubic yards to wetlands restoration sites in Marin and Solano counties. The ecological opportunities made possible by the airport and port expansion projects are significant. Still, many environmental organizations continue to oppose the idea of using restoration of the salt ponds as compensation for the loss of so much bay. Wetlands and open water are not ecologically equivalent, they note, and the airport should explore other alternatives. Still, an opportunity like the Cargill purchase does not come along very often. The company has, in fact, suggested it would be interested in selling its 19,000 acres for development if public agencies aren't willing to buy the property, meaning the opportunity to restore them would be lost. It is unlikely that the political muscle required to squeeze $300 million out of state and federal coffers will be exerted on behalf of a straightforward habitat purchase. Degraded marshland is not exactly an awe-inspiring redwood forest, and without the vested economic interest connected to a more reliable airport, chances of repeating the publicly popular Headwaters deal are slim. If Bay Area conservationists are to have any realistic hope of securing such a vast piece of bayfront land, they may have to accept the tradeoff. Contacts: San Francisco Estuary Institute: http://www.sfei.org/ Audubon Society, Golden Gate chapter: http://www.goldengateaudubon.org/Conservation/SFOExpansion.htm San Francisco International Airport: www.sfoairport.com/