Sonoma Creek


Sonoma Creek drains a 170 square mile watershed wedged between the Napa and Petaluma rivers. Sonoma volcanic rock dominates the eastern side of the drainage, and hot springs occur in a number of locations. Beneath the volcanic rock are Great Valley Complex and Franciscan Complex sedimentary rocks formed in ancient seas and waterways. The Petaluma Formation occurs along the west side of the valley in the Sonoma Mountains. This formation was created by a system of freshwater rivers which drained a series of volcanoes. These volcanoes were located east of San Jose. Due to movement along the San Andreas/Hayward fault system, the Petaluma Formation is now found in Sonoma Valley, many miles north of where it was created.

Oak woodland and chaparral with areas of coniferous forest cover the slopes of the watershed. Sonoma Creek and its perennial tributaries support steelhead trout. Tributary creeks include: Yulupa, Calabazas, Stuart, Mill, Agua Caliente, Carriger, Felder, Nathanson, Arroyo Seco, Rodgers, Fowler, Champlin, and Tolay creeks and Schell Slough.