Zim Zim Falls is a waterfall of about 130 feet in two tiers on Zim Zim Creek in the Knoxville Wildlife Area of northern Napa County, California, part of Berryessa Snow Mountain National Monument. It sits at the end of a long creek-side hike north of Lake Berryessa and has been open to the public only since 2005, when the wildlife area was expanded by 12,000 acres.
The falls
The cascade descends in a pair of tiered horsetails, with lidar measurements indicating a combined drop of about 130 feet and a tallest tier of about 110 feet. Earlier surveys listed 105 feet. Average flow is about 5 cubic feet per second; below the falls Zim Zim Creek runs to Eticuera Creek and on into Lake Berryessa.
Getting there
The trailhead is a large green gate just before mile marker 24 on Berryessa–Knoxville Road, with parking opposite. The approach road has uneven pavement and low-water crossings. The route follows a dirt road up the valley and fords the creek 8 or 9 times, so hikers should expect wet feet. The hike covers 7.4 miles round trip with 624 feet of gain on a trail rated moderate to difficult, with overgrown stretches where a GPS track helps. Longer options include an 11-mile loop through the Nevada Creek drainage and a 9.5-mile ridge route. The area is a Type C wildlife area managed by the California Department of Fish and Wildlife, and no hunting pass is needed to enter.
When to go
October through May brings comfortable hiking conditions, with water in the creek year-round and wildflowers in spring. Winter flooding can close the wildlife area for periods.
On site
The trail ends at a viewing area for the falls; getting to the lower view means scrambling cross-country along the creek. There are no restrooms. Dogs are allowed on a leash of 10 feet or less, horses are permitted, mountain bikes are not, and campfires are prohibited at all times. Hunting seasons run in the wildlife area. On the Nevada Creek loop, going too far downstream leads onto private property.
History and name
The name is a variant spelling of Zem Zem, a mineral spring in the Berryessa Valley that became a small resort and teamsters' camp during the Knoxville mining days. The spring itself was named after the Zamzam Well in Mecca.
Nearby
Devils Punchbowl Falls is about 16.6 miles away, Linda Falls on Conn Creek about 16.9 miles and Sonoma Creek Falls about 26.1 miles. Lake Berryessa lies to the south.
Distances are straight-line.