Photos: Pink salt ponds drawing scores of visitors off Bay Area trails

Pink salt ponds at Don Edwards San Francisco Bay Wildlife Refuge are drawing crowds wanting to check out the water’s Barbie hues, and that has created a problem as people have been wandering off the trails and trampling on sensitive areas. U.S. Fish and Wildlife has a simple yet clear message to the public: “Stay on the trails.”

In recent social media posts, the organization highlighted Pond A12 at Alviso Marina County Park. “These ponds provide a home to migratory and resident birds, including threatened and endangered birds like the cute western snowy plover. To keep you and the wildlife safe, stay on the Alviso Slough Trail to take your pictures. Please take pictures from the trail, not the pond.”

The Fish and Wildlife Service also offered the broad scientific explanation for the pond’s color: “It’s natural. Tiny microscopic organisms specialized to live in very salty water live here, including the microscopic algae known as Dunaliella salina and halobacterium.”

Meanwhile, Santa Clara County Parks explains on its website that a nearby levee project could be making A12’s water pinker than usual: “In 2021, Valley Water, the State Coastal Conservancy and the U.S. Army Corps of Engineers (USACE) began construction of the South San Francisco Bay Shoreline Project (Phase I) between the Alviso Slough/Guadalupe River and Coyote Creek. The levee construction requires very low water levels, therefore we did not replenish water into these ponds as they naturally evaporate throughout the summer. As a consequence, Pond A12 got saltier and pinker.”