The Sacramento-San Joaquin Basin is much larger (about 100x larger in area) than San Francisco Bay. Further, the rivers have existed for millions of years and the Bay only thousands. The watershed then is "the dog" and the estuary "the tail".

Estuaries are complex systems (so let's step back somewhat and take a broader view). By following the linkages--- atmosphere-watershed-estuary--- we are learning how and WHY freshwater discharge varies and how it affects average conditions in the Bay.

Estuarine system and
pathway of atmospheric
influence on estuary.

Most Variations in Discharge are Caused by Climate

Climate is the BIG SIGNAL in stream and river discharge records. This signal runs through the watershed and is ultimately carried into the ocean. There are many ways to trace it; these web pages sketch a few.

California Hydrology

Most of California's precipitation is in winter. It falls at low elevations as rain (winter discharge) and at high elevations as snow, which produces spring discharge as it melts. At intermediate elevations, discharge is a mixture of the two seasons (Cayan, Riddle and Aguado, 1993).