This cache is near the main parking area for the Wingo Unit of the Napa-Sonoma Marshes Wildlife area. The road this cache is near will take you to Wingo.
Just east of Schellville in the sloughs along Sonoma Creek is Sonoma Valley's ghost town of Wingo, CA. Originally known as Norfolk by the men and women who navigated the waterways, it is now known by the name used by the Sonoma Valley Railroad. Wingo once was a bustling train station for visitors arriving by steam boat from San Francisco, though now is just a cluster of cabins, workshops, barns and a train trestle.
Wingo was built for the purposes of the steamboat landing and was the location for the short-lived Sonoma Prismoid railroad. Wingo also contains the remnants of a Northwestern Pacific Railroad swing bridge, built during their short venture into Sonoma county in the 19th century.
A note about parking: To access this area, drive down Millerick Rd. off of Highway 121/Fremont Drive/Carneros Highway. Just after the Larson Family Winery, there is a sign saying that from October to May, the next 1.25 miles of the road is closed. I assume this is due to how muddy the road must get during the rainy season. However, on the day this cache was placed (12/28/13), the road was open - likely because we've had no rain! So if the gate is open, you should be able to drive all the way to the main parking area, assuming your car has high enough clearance (it is a rocky, bumpy, potentially muddy, dirt road). If the gate is closed or you're worried about taking your car down the road, you can park just after the Larson Winery and walk. This will add about 1.5 miles (one way) to your trip!