Marsh, Salt, and Sewage
Inhabitants of the South San Francisco Bay have long harvested salt from the sea. Native Americans, and later Spanish Missionaries, harvested salt from natural marshland ponds along the South Bay’s shoreline. Commercial salt production began in the mid-1800s, and by the 1930s over half of the historic salt marshes in the South Bay had been converted into stagnant, industrial salt evaporation ponds.
Industrialization sealed off much of the San Francisco Bay shoreline, north and south. And, as urban populations grew, so did their waste, which was dumped into the Bay.
Prior to the San Jose/Santa Clara Water Pollution Control Plant’s construction in 1956, the cities’ wastewater flowed freely into the stagnant South Bay and collected there. Today, the treatment plant cleans the sewage of 1.4 million people from eight Silicon Valley cities. Sewage travels to the plant in underground pipes from sinks, toilets, and drains inside homes, businesses and schools. The San Jose plant is a relatively large and model plant compared to most wastewater treatment plants in the U.S., with an above-standard industry treatment process that uses screens, microorganisms, carbon filtration, and chlorination to remove 99% of impurities. It does not, however, use an advanced filtration process like reverse osmosis that can remove pharmaceuticals.
Today, treated wastewater (near to the quality of drinking water) drains from the treatment plant into Artesian Slough: a tule reed-lined channel that runs out to the San Francisco Bay through a landscape of old salt ponds and partially restored natural wetland marsh and mudflats.
The old industrial salt ponds have actually preserved South Bay land from residential or commercial development. Just beyond the treatment plant’s borders, the Don Edwards National Wildlife Refuge is converting unused ponds into natural marsh wetlands. Old salt pond levees now serve as attractive nature trails and convenient public access points to the picturesque Artesian Slough’s valuable waters.