For the millions of travelers whose planes land here each year, the salt ponds of the San Francisco Bay appear like some checker-board artwork, their chartreuse to orange-red hues shimmering at the edge of the estuary. For environmentalists, these ponds -- some diked as early as the days of the Ohlone Indians who lived alongside the bay -- represent the greatest single opportunity to return the shoreline to its natural state. In October, after two years of hints and rumor, the international food and agricultural company Cargill Inc. announced that it would sell 18,800 acres of salt ponds and salt extraction rights in Alameda, San Mateo, Santa Clara and Napa counties. Turning salt ponds to wildlife habitat might be the biggest bonanza in the campaign to add 60,000 acres of tidal marshes around the bay, bringing the total to 100,000 acres, resource managers say. At one time, the bay was ringed by 190,000 acres of marshes. Yet, three controversies swirl around the Cargill proposal. The most politically charged controversy involves suggestions that the land deal be paid for by San Francisco International Airport, in exchange for the right to build new runways that would fill the bay by as much as two square miles. In addition, some say Cargill is suggesting too high a price tag for the deal. And, finally, some environmentalists want more of the ponds returned to the refuge than Cargill is willing to sell.

LARGEST RESTORATION

Public acquisition of the salt ponds would set in motion "the largest wetland restoration being proposed in the Bay Area and certainly on the West Coast," according to Marge Kolar, manager of the Don Edwards San Francisco Bay National Wildlife Refuge. She and others envision brand new grounds -- from tidal marshes to mudflats -- for fish and plants, for the endangered California clapper rails and salt marsh harvest mice, and for the popular shorebirds, songbirds and waterfowl. The Cargill deal could provide a chunk of that ambitious shoreline restoration goal in "one fell swoop," Kolar said. Lori Johnson, a Cargill spokeswoman, agrees that the transaction would have immense effects. "If this deal goes through, and Cargill gets the price it wants, almost all of the shoreline would be in public ownership" at the southern tip of the bay near Fremont, Alviso and Redwood City. Cargill Inc. announced that it would sell outright 14,800 acres of salt ponds. About 13,400 acres of the land lie in Alameda, Santa Clara and San Mateo counties in the South Bay. About 1,400 acres lie in Napa County in the North Bay. Of the 12,000 acres of Cargill's working ponds that lie within the San Francisco Bay National Wildlife Refuge, Cargill would sell salt extraction rights on 4,000 acres and retain extraction rights on 8,000 acres. It would keep 3,000 acres of land that it owns in Newark, where it runs a salt plant.

RETURNING PONDS TO WILDLIFE

Salt making is an ancient trade around the bay, dating to the early Indians who once tended about 2,000 acres in the south bay. In the 1850s, small works produced salt for gold mining. Leslie Salt Co. came to the bay in the 1930s. In 1977, the federal government condemned 15,347 acres of Leslie Salt's land, including 12,000 acres of diked salt ponds, for the national refuge, which had been established five years earlier. As part of the $7.6 million condemnation deal, Leslie retained the rights to extract salt in perpetuity from the ponds. In 1978, Cargill bought out the Leslie holdings, including the right to extract salt from those salt ponds in the refuge. The environmentalists hoped that one day, when salt was no longer a lucrative business, these ponds would return to tidal marshes and old sloughs. Now that Cargill is selling some of the land and salt rights, many environmentalists want all of them. "We didn't want to buy the ponds just so Leslie could continue salt production. Our hope was that before long (the ponds) would be for wildlife only," said Janice Delfino, a Castro Valley conservationist who with her husband, Frank, began lobbying for the refuge in the late 1960s. "We'd like to get Cargill out of there," she said.

$300 MILLION PRICE TAG

Also at issue is the amount of money Cargill wants for its ponds. The company says it should get as much as $300 million for about 18,000 acres. That is more than $16,000 an acre, nearly three times the going rate, environmentalists say. Marc Holmes, director of wetlands restoration at the Bay Institute of San Francisco, a San Rafael environmental group, said Cargill is "asking way too much, an exorbitant price"' for its wetlands. "The true value of a wetland has been established over the past two decades in court cases," Holmes said. "They're considered waters of the state. You can't put houses in these salt ponds. The average price is more in the vicinity of $4,000 to $6,000 an acre. The highest is $10,000 an acre. "The government should spend no more than $100 million, and spend another $200 million to finance the restoration," said Holmes. But Cargill says these lands are rare and valuable. When developers and agencies need to win approval for their construction projects, they can offer to buy, restore, then donate these lands as a way to mitigate any damage their development will do to the bay. The Santa Clara Water District paid as much as $21,000 an acre when purchasing Cargill land for flood control this year. And a private developer in the last year paid $600,000 for six-tenths of an acre to mitigate damage from building houses, said Cargill's Johnson. That doesn't count, said Holmes. Appraised values are determined by sales to private buyers and not to public agencies, he said. "Even if they did count, there's a very limited demand for salt ponds. We're talking about more than 10,000 acres available here. Nobody's going to come along and offer that much an acre for that many acres. The only rationale is if you're buying the business. Cargill isn't going out of business, they're just consolidating," Holmes said. Cargill's intent "has always been to remain in salt production in a very significant way in San Francisco Bay," said Johnson. "We need the salt ponds so we can stay in business. California and the West Coast are very important markets for us. Salt is a market that tends to be very regional because transportation costs are high."

AIRPORT'S SUGGESTED DEAL

The future of the Cargill salt ponds has become interwined with the proposal to expand the runway system at San Francisco International Airport by further filling the bay. Former Airport Director John Martin tried in 1998 to win environmentalists' support to build a new runway in the bay in exchange for the airport's restoring the Cargill salt ponds. Martin said the airport had $200 million that couldn't readily be found elsewhere to put toward the restoration. Most environmentalists objected to the trade-off. Before it could even get consideration of a proposal to fill the bay for a runway, the airport was legally required to prove that its current flight delay problems could be solved no other way. All other discussion, including possible mitigation by purchasing the salt ponds, was premature, environmentalists said. The airport hoped -- and still hopes -- that the promise of money for wetland restoration would distract attention from the case that it needed to make for the largest bay fill in generations, they said. MAKING A CASE Kandace Bender, city spokeswoman for airfield development, agreed that the airport still needs to make its case. "We are working diligently with environmentalists, scientists and regulatory agencies to ensure that all questions are addressed as much as possible," Bender said. Still, she said, the airport is doing internal studies that examine how bringing back Cargill's and other wetlands would make up for losing bay waters to a runway fill project. "Mitigation would be part and parcel of any runway built, and this is an historic opportunity to restore many of the bay's lost wetlands," Bender said. "The airport's philosophy is that one does not have to make a choice between the economy and the environment. Rather, it's about both." Mayor Willie Brown has been outspoken in favoring expansion of the runways as the option, and retoring Cargill's salt ponds as way to win approval. City officials and legal consultants helped craft legislation that was intended to ease environmental review of bay fill for runways. In hearings over a law that would authorize money for the purchase of Cargill's wetlands, author Assemblywoman Carole Migden, D-San Francisco, argued that securing the ponds would help win approval for runway expansion. Brown testified that the Cargill property was a key to enlarging the airport, crucial for San Francisco's economic health. Migden's original bill asked for $150 million, but was sent to the governor as $30 million. He reduced it to $25 million. "The airport is still putting an inappropriate and premature emphasis" on expanding the runways, said David Lewis, executive director of Save the Bay. "The project and its impacts are still not defined," Lewis said. "The less environmentally damaging alternatives have not been explored. The airport would like us all to think that we can't buy the wetlands without its help. That's simply not true." --------------------------------------------------------------------------------

What Colors Salt Ponds

The dramatic palette of salt pond colors reflects a complex interaction of plants, animals and salinity. Colors range from pale green to a deep coral pink. Microorganisms create these colors, changing their own hues in response to increasing salinity. -- Low to mid-salinity: Green algae lends the water a green cast. -- Increased salinity: Dunaliella algae proliferates and turns the ponds a lighter shade of green. -- Mid- to high salinity: High salt concentrations actually cause the Dunaliella to produce a red pigment. Salt-loving, or halophilic, bacteria, also contribute red tints and purplish-red hues in brines. -- Brine shrimp: Millions of tiny brine shrimp in mid-salinity ponds add an orange cast to the water. -- Weather: When wind creates choppy conditions, the colors appear murkier. Heavy rain can dilute the brine, causing the colors to shift toward the hues found in lower-salinity ponds or even turn the water clear. Source: Cargill Salt Chronicle Graphic