Project Brief


About Napa River




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Bren School


The Napa River runs 55 miles from the headwaters of Mt. St. Helena in the Mayacamas Mountain Range to the San Pablo Bay.   Spanning 426 square miles, the Napa River watershed and its 47 tributaries are spawning grounds for the endangered Chinook Salmon and Steelhead Trout and provide a habitat for dozens of other endangered and threatened birds, mammals, reptiles, fish and plants.  The climate in the Napa region is Mediterranean characterized by warm, dry summers and cold, wet winters.  Rainfall in the region occurs mostly during the winter and early spring.  

The Napa Riverís peak flows are correlated with the areaís rainfall, producing peak flows from December to February.  Within the watershed, the highest rainfall occurs on the western side contributing to landslides, increasing erosion and nutrient transport from sources to the Napa River.  Lands around the Napa River are divided into a variety of land use types.  Evergreen, deciduous and mixed forests cover approximately 35 percent of the watershed, residential and commercial areas combined cover approximately 8 percent, all agricultural cover types combined account for nearly 19 percent of the watershed, and grasslands and other herbaceous cover types often used as rangeland cover about 22.6 percent.