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Your Gallinas Creek Watershed

DO YOU KNOW WHERE YOUR STORM DRAINS FLOW?

The Gallinas Creek watershed is an almost 11 square mile basin on the eastern side of Marin County between the Miller Creek and San Rafael watersheds. It has two main drainage areas, divided between the North and South Forks that connect just east of the airport where they wind to the east past Buck’s Landing before flowing out in San Pablo Bay. The watershed boundary also wraps around the bay shore to include China Camp State Park and McNears Beach County Park that also drain to San Pablo Bay.

Tributaries to the North Fork gather from the slopes of the Terra Linda-Sleepy Hollow Divide Open Space Preserve and collect into the concrete channels along Del Ganado Avenue and Manual T Freitas Parkway. The North Fork then flows under Highway 101 where it becomes a natural channel, winding northeast between McInnis Park and the San Rafael Airport.

The South Fork tributaries begin in Los Ranchitos collecting and crossing under Merrydale Road and Highway 101 where it runs along Avenue of the Flags and around the Marin County Fairgrounds and Santa Margarita Island. It’s joined on the back side of Lagoon Park by Armory Creek which flows down from San Pedro Mountain Preserve crossing under North San Pedro. Meadow Creek’s tributaries come down to Granlee Road and Oxford Drive and collect down Meadow Drive, connecting to the South Fork at Santa Margarita Island.

The upper slopes of the watershed are composed primarily of annual non-native grasslands interspersed with mixed evergreen forest and oak-bay woodland, coastal scrub, and small outcroppings of serpentine habitat. As the two forks make their way down to the valley floor upstream of Highway 101, they are restricted to highly modified rectangular and trapezoidal channels, and tributaries are restricted to underground storm drains. Downstream of Highway 101, the creek is channelized for a portion before regaining the natural bed and banks. Some marshes adjacent to San Pablo Bay are leveed. The lower tidal marsh habitats represent some of the largest remaining tidally influenced habitats in the San Francisco Bay region and provides the most important biological resources within the watershed. Along the southern watershed boundary, upslope of Santa Venetia, there is a large area of oak-bay woodland. This is continuous with China Camp State Park and provides important habitat for woodland species.

Santa Margarita Island at the end of Meadow Drive, and the trails throughout the lower watershed marshlands are the best way to view the creek. These trails can be accessed at McInnis County Park, Santa Venetia Levee Trail around Santa Venetia Marsh Preserve, and Buck’s Landing County Park just before the mouth to the bay. The wetlands at McInnis Park form the divide between Miller Creek and Gallinas Creek and both can be viewed by that trail system.

The marshlands support several special-status animals, including San Pablo song sparrow, Ridgway’s rail (formerly called California clapper rail), California black rail, and Salt marsh harvest mouse. The watershed is also home to the common wildland–urban interface mammals with deer, coyotes, skunks, and raccoons found throughout the watershed. River otters are known to frequent the channels near the bay.

Birdlife is abundant and waterfowl frequent the tidal sloughs. Rails and shorebirds are common along the edges in marsh habitat. The mouth of Gallinas Creek supports one of the largest populations of Ridgway’s rail within San Pablo Bay. Overall, the watershed is known to support 86 breeding bird species. Herons and egrets are also known to nest in the watershed. Audubon Canyon Ranch has monitored heron and egret nesting colonies since the early 1990s.

Remember, storm drains connect streets to creeks. Simple changes can make a big impact. Gallinas Creek Watershed is Ours to Protect.

LEARN BEST PRACTICES FOR PROTECTING OUR CREEKS AND RIVERS HERE >

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