Day

May 25, 2023
25
May

Tackling Pollution

Though the Clean Water Act did an amazing job of reducing wastewater and stormwater pollution of the San Francisco Estuary, some contaminants remain thorny problems.  Legacy pollutants like mercury washed into the watershed from upstream gold mining, PCBs from old industrial sites, and selenium from agricultural drainage in the San Joaquin Valley, linger in the sediments, nearly impossible to clean up.  Emerging contaminants from contemporary lifestyles such as herbicides, flame retardants, and fire-fighting foams are being linked to human health problems, while microplastics are turning up everywhere from fish guts to creek bottoms to newborns. More recently, nutrients from both farm and sewage discharges have become a particular challenge for the Estuary. Long protected by its sediment-clouded waters, a recent...
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image of bioretention site
25
May

Greening Stormwater

When rain runs off into the San Francisco Estuary from streets, parking lots, and other hard surfaces, it can carry a toxic soup of contaminants—oil, grease, and myriad other chemicals that may start off as pollutants in the air but end up on the ground where they can they then be washed into water bodies in storms. For the past three decades, Bay Area scientists have tracked and analyzed these contaminants to determine exactly what they are and how they affect water quality. Water quality agencies, meanwhile, have developed increasingly stringent regulations—such as TMDLs, or Total Maximum Daily Loads and other mechanisms—to try to control them. In more recent years, the practice of Green Stormwater Treatment—the use of soil and...
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salmon
25
May

Sustaining Salmon

By the time Estuary News debuted in 1993, the Central Valley’s once abundant runs of Chinook salmon had been severely depleted by dams, diversions, pollutants and predation by non-native fish. Sacramento River winter-run fish were federally listed as endangered in January 1994; the Central Valley spring run was listed as threatened in 1999 and the fall run is identified as a species of concern. Protecting and rebuilding these populations has been a lodestar for many, if not most, of the efforts to restore the Bay and Delta, beginning with 1992’s Central Valley Project Improvement Act. Over the decades, armies of scientists, engineers and water managers have sought to better understand and mitigate the threats to this iconic fish, while lawyers,...
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25
May

Restoring Habitats

Early efforts to restore the San Francisco Estuary, before the federal Clean Water Act and Endangered Species Act changed management priorities in the 1970s, focused on preserving marshes for waterfowl hunting, protecting river reaches for fishing, and growing trout and salmon in hatcheries. By that time, the estuarine ecosystem had been so severely altered by draining, diking, damming, farming, urbanization, species invasions and water supply projects that there was little left to restore. Restoration to some pristine former state was soon deemed an impossibility. Nevertheless, new mandates forced planners to consider restoring a variety of habitats used by endangered fish, birds and wildlife, to manage dam releases to provide flows and cold water to migrating species, and to reduce pollution...
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25
May

Controlling Invasions

San Francisco Bay has been called the most invaded Estuary in the world. From Chinese mitten crabs to zebra mussels from Europe to Atlantic cordgrass from the East Coast, the Estuary has been colonized by myriad animals and plants from other parts of the country and world. Water hyacinth now clogs Delta waterways; Asian clams regularly consume all the fish food in the water column; water primrose is carpeting over native flora. Many alien animals arrived in ships’ ballast water or aquarium water dumped by unknowing home hobbyists while plants like Atlantic cordgrass were introduced intentionally by the U.S. Army Corps of Engineers in restoration projects, from which the plants then hybridized with Pacific cordgrass, creating a menacing invader. But...
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