| Arroyo Seco | |
| Pushpin Map: | California |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of Arroyo Seco Creek in California |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | California |
| Subdivision Type3: | Region |
| Subdivision Name3: | Sonoma County |
| Subdivision Type5: | City |
| Subdivision Name5: | Sonoma, California |
| Source1 Location: | 40NaN0 northeast of Sonoma, California |
| Source1 Coordinates: | 38.3356°N -122.4175°W |
| Source1 Elevation: | 1345feet |
| Mouth: | Schell Creek |
| Mouth Location: | 40NaN0 south of Sonoma, California |
| Mouth Coordinates: | 38.245°N -122.4347°W |
| Mouth Elevation: | 13feet |
| Basin Size: | 11.4sqmi |
| Tributaries Left: | Haraszthy Creek |
Arroyo Seco is a 6.9adj=midNaNadj=mid[1] tributary stream to Schell Creek in southern Sonoma County, California, United States. In Spanish arroyo seco means "dry stream."Arroyo Seco Creek drains a portion of the western slopes of the southern Mayacamas Mountains. Its 11.40NaN0 watershed,[2] along with the entire Mayacamas mountain block, was formed in the Miocene era by volcanic action and with tectonic uplift about 12 million years ago.
Soils of the immediate streambed and its vicinity are classified as the riverwash series, recent deposition of sands and gravels.[3]
Arroyo Seco Creek springs near the Napa County line about 40NaN0 northeast of Sonoma, California. It flows southward, emerging from near Sonoma Valley Hospital. After a confluence with Haraszthy Creek, it crosses under State Route 12 near Schellville, California, where it flows into Schell Creek. Schell Creek discharges to a network of sloughs that eventually empty into Sonoma Creek, which in turn empties into the Napa Sonoma Marsh and San Pablo Bay.