ABSTRACT
Today the San Francisco Bay Area is one of the largest metropolitan areas in the United States. All of those people need food, shelter, transportation, employment, and other things, and all of that activity has taken a toll on the Bay and surrounding areas. The land has been paved and developed. Landslides and the occasional earthquake still cause changes. The air is much worse. Air pollution is significant here despite years of attempts to improve it. The increasing number of wildfires have also degraded the air quality. However, the Bay and river waters themselves have been most affected by humans. The amount of sediment was greatest during the Gold Rush days. Now the quality of the Bay water is influenced by the amount of freshwater allowed to reach the Bay after the various upstream demands are satisfied. Legacy mercury and modern pollutants poison the water. Raw sewage and agricultural runoff contribute to algae blooms that reduce oxygen levels. All of these affect the plants and animals in the Bay.
