Biology Reference
In-Depth Information
San Pablo
Bay
Suisun Bay
Rivers
Central Bay
South Bay
Lower South
Bay
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20 miles
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Map 6. The sum of PCBs found in bay sediment (parts per billion, or ppb) between
2004 and 2008, based on 235 data points in the Regional Monitoring Program.
Maximum concentrations (30 ppb) occurred in the South Bay in 2008, with a bay-
wide average in the same year of 9.4 ppb. (S.F. Estuary Institute)
web. In other words, organisms that couldn't live in the bay 30 years ago
have been making a comeback.
Clean Water Act investments delivered immediate reductions in or-
ganic and bacterial pollutants, as well as in some heavy metals. Yet other
metals, and chemicals such as DDT and PCBs, persisted in sediment and
water samples. Though banned in 1972, DDT drove several bird species to
the brink of extinction, weakening the eggshells of the California Brown
Pelican and Peregrine Falcon until they broke during incubation. Califor-
nia's Brown Pelicans proved especially sensitive due to a combination of
their reliance on ocean foods such as sardines and heavy DDT dumping
on the ocean floor near their nesting areas. Their California numbers
plummeted from about 5,000 pairs in the 1950s to just a few hundred pairs
