A stark angular wooden construction with fan blades rises
out of the murk. At first glance it looks like a medieval instrument of
torture, or a failed attempt at early flight.
It is neither, of course, though it is an important
iteration of an ancient technology; it a wind-driven Archimedes screw pump, a
remnant of the once thriving trade in salt endemic to the East bay.
Long before white settlers discovered the beds of
evaporites along the sea shore near modern day Coyote Hills and Edwards reserve,
Ohlone people traversed the estuaries in reed canoes, harvesting the naturally
deposited sea salt by scraping it from plants or simply scooping it into woven
baskets. When the Gold Rush drew thousands to the Bay Area in the early 1850s,
Swedish immigrants were among the first to realize the area’s commercial
potential. Salt was in demand at the time, not only for seasoning, but food
preservation, tanning, and a host of industrial uses.
In 1852, Scandinavian sailor Josh Johnson expanded the
naturally occurring ponds of the estuary by having Chinese laborers drain the
marshes and create levees from wood, stone, and mud. At high tide the waters
would flow through gates in the levees, then remain there to evaporate, leaving
“bay salt” behind for collection.
Johnson sold his outfit to Swedish sailor August Ohleson
in 1872, who changed his name to Andrew Oliver. Oliver’s family provided salt
to tanneries, food processing, and packaging companies until 1982. It was
Oliver who introduced the wind-driven screw pump to his salt production
process. The pump was used to transfer water from one pond to another. Oliver
also introduced a process of spraying sea water onto logs, where it would
evaporate and leave salt to be scraped off, in imitation of the Ohlone method,
but on a larger scale.
At the turn of the twentieth century there were about 17
salt businesses within the fifteen miles between San Leandro Creek and
Centreville. The average wholesale price was about $35 per ton, with 17,000
tons produced annually. H. H. Wood’s 1888 history of Alameda County values the
industry at more than one-and-a-quarter million dollars, with over a hundred
workers employed in the trade.
The early years of the salt trade encountered foreign
competition. Wood notes that speculators abroad would ship commodities to be
auctioned at the port of entry. In this way, salt from Liverpool and the East
came to California. Because of the abundance of native product, the allure of
imports rested solely in the low price they had fetched at auction. Soon,
however, the imports gained ground because of their higher quality. Only with
improvements in processing introduced by Oliver and others did the quality of
native salt equal the imports, and at a better price.
Improvements in salt-making included better management of
the salt pond levels and salinity, which the screw pump facilitated. Archimedes
(287–212 BCE) is credited as the inventor of the screw pump. It is most often
used in irrigation, and consist of spirals encased in cylinders that raise
water when turned. They have been in constant use for over two thousand years;
the earliest versions found in Rome, Eqypt and Japan were turned manually. In
the seventeenth century, the Dutch applied wind vanes to the pumps, a design
forerunner to those built by Oliver, of which two survive. In 1984 the American
Society of Mechanical Engineers designated an Oliver pump, restored in 1978, a
Historic Mechanical Engineering Landmark. The original location was on a site
now owned by Cargill in Newark, but In November of 2016, ASME and Cargill
commemorated the moving of the pump to its new location at the Hayward
Shoreline along the Oliver Brothers Salt Loop Trail (the commemorative 1984
plaque got a polish, too.)
Today, airline passengers arriving over the East Bay can
spot from the air the salt marshes that still exist, due to their intense
color. Microorganisms of different colors and saline tolerances, as well as
brine shrimp, provide the rich hues, which can change with the weather. At one
time over 80% of the Bay’s wetlands succumbed to salt farming and related
industry, but in 2003 Cargill, Inc. who owned more than 16,000 acres of the
affected wetlands sold 15,100 acres to State and Federal agencies as well as
private foundations, like the South Bay Salt Pond Restoration Project, who are
in the process of restoring them to their tidal wetland beginnings by
reintroducing bay water to the ponds and attracting wildlife.
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