Explore Salt Ponds and Marsh at Alviso Marina County Park

Alviso, Ca – Connect with a site that’s a part of one of the largest tidal marsh restoration projects on the west coast. Alviso Marina County Park was formerly an industry-dominated site, but now serves as an amazing entrance to the greater Don Edwards San Francisco Bay National Wildlife Refuge.

About the Park

Alviso, Ca – Santa Clara County Park 

Science Spotlight: Leopard Sharks at Alviso

When I first learned that there were actual sharks around Alviso, I was in total shock. To me, the idea of the perfect habitat for sharks had always been the open ocean. Thus, you can imagine my surprise when I learned that the area is home to leopard sharks.

Leopard sharks are the most common sharks in the San Francisco Bay estuary, with a range that extends from Oregon to Mexico. They can grow to lengths of up to 7 feet, and feed on invertebrates and fish. To feed, they make a daily migration to shallow areas during high tides.

The San Francisco Bay Area lost much of the tidal marsh and shallow areas utilized by the leopard sharks to development for harvesting salt. As these tidal marshes are restored, researchers are finding that the leopard sharks are returning.

Leopard shark; Source: © Nathan Rupert, 2009, Flickr Photo Album, some rights reserved.

Park History

Visiting Alviso truly feels like a blast into the past: on your way to the park, you pass by an old cannery site, the warehouses, and a Victorian-style home. The area that is now Alviso Marina County Park used to be receive drainage rich in mercury from the New Almaden Mining District. The site also used to be a heavily-trafficked port area supplying San Jose and a launching point for steamboat passage to San Francisco. When these operations shut down, the area was transformed into salt ponds for salt harvest, operated by the Cargill Salt Company.

The area is now rich with wildlife, providing a feeding and nesting area for many species of birds. Alviso Marina County Park has become a part of the nearby Don Edwards San Francisco Bay National Wildlife Refuge. Today, the area is part of the South Bay Salt Pond Restoration Project (SBSPRP), one of the largest tidal marsh restoration projects on the west coast. Restoration offers new habitat for California wildlife and offers visitors the chance to see nature reclaiming a formerly industry-dominated area.

For more detailed information on the history of Alviso Marina County Park, check out this article by the Mercury News.

Visit the Park

Please note that there is no entrance fee to enter the park. Dogs are now allowed on trails or walkways. For more detailed information on where dogs are and aren’t allowed, check out the park map.

Alviso Marina County Park serves as the entrance to the greater Don Edwards San Francisco Bay National Wildlife Refuge. We encourage you to explore that area as well, time permitting.

Here are some helpful resources to plan your visit:



A San Francisco Butterfly: The Variable Checkerspot

Cover photo: © Jamie Chavez, 2013, some rights reserved.

Learn more about the small butterfly that’s making a comeback around the San Francisco Bay Area.

Cover photo: © Jamie Chavez, 2013, Flickr Photo Album, some rights reserved.

The Presidio’s population of variable checkerspots became locally extinct in 1978.

Variable checkerspots are a part of a program working to reintroduce native species back to the Presidio in San Francisco. The Presidio’s checkerspot population became locally extinct in 1978 due to the loss of habitat. Park restoration efforts are currently working on the Presidio’s native habitats, resulting in 50 acres of native habitat restored thus far. With the hopes of bringing the butterflies back, 1,500 caterpillars were collected from other parts of the Bay Area and reintroduced to the Presidio in 2017.

If successful, the Presidio will become one of two areas in San Francisco that hosts the variable checkerspot butterflies (the other at Laguna Honda Reservoir). The primary cause of their decline in the area has been the loss of habitat across the city. With efforts such as those at the Presidio, we can hope that we’ll be seeing more of this beautiful butterfly.

Variable checkerspot caterpillars are spiny, and the butterflies are black with checkers.

Variable Checkerspot caterpillars are mostly black, with light dots that form bands along their body. They are covered in black and orange spines.

Butterflies are mostly black-brown, with yellow and orange checkers. Their wingspan is 1.25 – 2.25 inches.

Variable Checkerspot Caterpillar
Variable Checkerspot caterpillar on an English Plantain at Purisima Redwoods Preserve

Variable checkerspots live on the west coast of the U.S.

Variable Checkerspots can be found along the Pacific Coast,and as far inland as Wyoming and Colorado. They prefer chaparral habitats (semi-arid areas composed of mostly shrubs), open forest areas, and alpine tundras.

Variable checkerspots use many native and non-native plants for food.

Caterpillars will use beeplant, Indian paintbrush, snowberry, honeysuckle, monkeyflower, English plantain, and many others as host plants. Adults will feed on nectar from California Buckeye, Squawbush, Yerba Santa, and thistles (to name a few).

Resources to learn more: