Last Sunday my wife and I paid a visit to the old salt ponds, down in the Napa marsh.
We hadn't been there in a while, but we remembered the way: you turn south on Buchli Station Road from Las Amigas Road in Carneros, and drive to the end. When you get there, you find a small parking lot, and before you there is a broad, flat expanse of marshlands and diked ponds. There are not many people around, nor is there much indication of human activity. There are dikes, obviously not nature's work, but any further infrastructure is a bit hard to spot at first. You do see a restroom building and a collection of small signs put up by the State Department of Fish and Wildlife.
It's very quiet there, a pleasant refuge in pandemic times. The first thing we noticed was a large group of swans on Fly Bay, to the east of us as we walked south along a levee. My wife, who pays close attention to birds, was very surprised to see them. She later identified them as tundra swans. As we continued walking, we did find some more tangible infrastructure, a collection of valves and pumps designed to transfer water between ponds. There was also an interesting small building that probably contained electrical equipment. All this equipment looked rather new -- and expensive -- and we entertained ourselves with speculations on how it was used.
There have always been wetlands alongside the lower Napa River, roughly at the latitude of American Canyon but mostly across the river to the west. However, in the mid-twentieth century we found out that you could use the natural effects of sun and wind to produce industrial salt here by evaporation, and large areas of the Napa marshes were added to the list of Bay Area wetlands sacrificed to commercial use. The Cargill company operated salt ponds there until the 1980s. However, the Cargill property was bought by the State of California in 1994, and since then the State Department of Fish and Wildlife (formerly the Department of Fish and Game) has been working to restore the salt ponds to wetland habitat.
It's a big job, essentially to undo the work of several decades spent concentrating the salt. There are around a dozen separate ponds, gradually increasing in salinity as you get further from San Pablo Bay, ranging from the sodium chloride concentration in bay water up to a concentration ten times as great. The higher the salinity, the fewer plants and animals there are, and the restoration challenge is that much greater.
I found out about the restoration project when I started working as a hydrologist with Napa County Resource Conservation District (RCD) in 1995. At that time the State was just starting this impressive project.
Today the recovering salt ponds form part of the Napa-Sonoma Marshes Wildlife Area, which can be conveniently accessed from the end of Buchli Station Road in Carneros, as we did. I believe it is open for hiking and wildlife viewing all year round, but if you want to bring a dog (which should be leashed, of course) you have to avoid the spring nesting season for ground-nesting birds. Hunting is allowed during hunting season; special rules apply to hunting dogs.
Bob Zlomke