WT1 – Rattlesnake Island


Photo of Stand up paddleboarding near Rattlesnake Island.

Stand up paddleboarding near Rattlesnake Island


Water Trail Map of Rattlesnake Island
Length: 4 Miles Round Trip

Time: Approximately 2-3 hours

Experience Level: Intermediate through advanced

Launch Area: Clearlake Oaks Boat Launch, Island Park Drive off Hwy 20 East, Clearlake Oaks, CA 95423

Trail Highlights
– Views of Mt Konocti
– Migratory waterfowl route
– Wetlands, tule reeds
– Historic cultural resources
– Rich wildlife viewing
– Islands and canals
– Picnic spots

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Trail Description:
For the naturalist and those who want to savor breathtaking beauty, this is a beautiful loop around Rattlesnake Island, past the historic Sulphur Bank Mercury Mine and wetlands, and back through the canals of “The Keys” in Clearlake Oaks.

On calm days, this is an easy paddle for all experience levels. On windy days, however, it is for experienced paddlers willing to battle heavy winds and large waves. In the summer, mornings are best since the midday sun can become intense and strong winds typically pick up in the afternoon

Trail Route:
Park and launch at the Clearlake Oaks boat ramp on Island Drive just off of East Highway 20. As you begin your paddle out toward Rattle snake Island (1), Mount Konocti dominates the background – a dormant volcano that sits at an elevation of 4,300 feet. Geologists estimate its first eruption approximately 600,000 years ago and evidence suggests the most recent volcanic activity took place within the last few thousand years.

Archaeological evidence suggests Native American activity on Rattlesnake Island dating back 8,000 years. While privately owned, this island’s significance as the ancient burial ground and village site of the Elem Pomo, prompted a recent nomination to the National Register of Historic Places. Descendants of the early inhabitants live 500 feet east by Sulphur Bank.

For birdwatchers, the winter months beginning in mid-December through March, can be an unforgettable paddling experience. Migratory groups of cormorants, grebes, gulls, coots, buffleheads, egrets, herons, and ducks are just a few of the waterfowl seen dotting the water, at times numbering in the tens of thousands. And it’s not unusual for lucky paddlers to see a ribbon display of several hundred American White Pelicans slowly soaring overhead. But the summer still holds many resident waterfowl, including osprey typically perched on bare tree trunks. Families of otter and the occasional mink often play along the shoreline, as do the island’s resident goats and peacocks.

Rattlesnake Island is considered by many to be one of the best fishing locations on Clear Lake, which is noted for largemouth bass and catfish. Most days, fishing boats dot the perimeter from sunrise to sunset.

Circling around the island’s eastern end, the historic Sulphur Bank Mercury Mine (2) comes into view. Activity dates back to the California gold rush days in the mid 1800s, when mercury was essential in the process of extracting gold from ore. Chinese laborers removed the ore from deep mine shafts, which changed to open-pit mining during the 1920s.

Over the decades, geothermal inflows and rainwater filled the pit, becoming highly acidic and leaching dissolved mercury back into the lake. Bacteria present in the sediment converts this to methyl mercury, which is easily absorbed by wildlife and fish. The Sulphur Bank Mercury Mine became an EPA Superfund Site in 1990. While few remnants of the mine or equipment remain, the location is a California historic landmark, although currently is fenced off to the public.

Heading back around the wetlands just north of the Elem Indian Colony (3), watch the shoreline. Osprey – and the occasional eagle – can be seen perched for prey in tall, bleached-out trees. Paddle past secluded Dollar Island (4) and catch your breath by perching on one of the small rocky crags while you enjoy the view, but beware of poison oak. At this point, you can choose to head back toward the boat launch, but avid birdwatchers may opt to paddle into the Keys to loop into a small tule marsh (5). In the morning, calling birds – such as blackbirds, coots, and herons – overpower the sounds of motorists along nearby Highway 20.

Head back toward the boat ramp by entering the main Key near the campground at the southern tip of Stubbs Island (6). Keep heading to the left through the Keys and just before Clarks Island (7), a weeping willow hides the Island Drive bridge – you can choose to paddle under this to return to the boat ramp, or take a picnic break on Clarks Island, which is a County-owned park.

Best done in the winter, spring, or early summer; naturally occurring algae and aquatic weeds can hinder your paddling efforts during late summer and fall. On windy days, the Keys can be a nice, easy jaunt through the canals, or a great choice if you’ve finished with Rattlesnake Island but aren’t yet ready to stop. Great for waterfowl birdwatching, particularly in the winter.

Alternate launch point: This loop also may be accessed from the Short Street boat launch (8), located off Highway 20 across from Nylander Park. After launching, head toward the lake through the Keys under the Island Drive bridge, which opens to the lake and the Clearlake Oaks boat ramp.