Roy's Redwoods restoration hopes to replenish aquifer

David Briggs
A restoration of the San Geronimo open space preserve will slow the flow of the seasonal Larsen Creek with logs, trail structures or fill, restoring a floodplain that absorbs more rainwater.  
08/07/2019

“Slow it, spread it, sink it.” It’s the guiding concept for the restoration of Roy’s Redwoods Open Space Preserve, a project underway by the county with help from One Tam. Last Wednesday, the project’s design team updated residents on the design alternatives, which aim to provide a more immersive visitor experience while enhancing the forest’s ecological health, and in particular, its stream flows. 

A spiderweb of social trails has compacted soils, exposed sensitive tree roots, left a virtually nonexistent understory of vegetation and constrained Larsen Creek, a tributary of Lagunitas Creek in the San Geronimo Creek watershed. Increased levels of sediment are carried through the park, and fast-flowing waters during the winter fail to nourish the redwoods. 

“That’s not really what we want to see in a natural flood plain,” Jon Campo, the county’s senior natural resource manager, said at the meeting, held at the San Geronimo Valley Community Center. “We’d rather see a multi-threaded, slow-moving water system.” 

Embracing the hydrologic concept of “slow it, spread it, sink it,” the team will seek to raise the water table by diverting large, fixed flows, so that streams meander flexibly through the forest, slowing down the waters and recharging the aquifer. This type of restoration, called Stage 0, may be the first of its kind in the Bay Area, Mr. Campo said. 

As part of the restoration, the team will phase out redundant or unsustainable trails in the 293-acre preserve, leaving a set of four connected loops that run by the old-growth redwood forest’s high-interest areas. A section of the trail will be firm and flat so it can be accessed by handicapped visitors; for adventurous hikers, an array of fallen logs and boardwalks will cut across the meadow, which will help in both healing the forest and maintaining the playfulness of the park. 

“We’re placing logs that will deflect flow, but they will also give us a way to scramble over anywhere there is a wet section on the trail,” said Erik Stromberg, a consultant from Restoration Design Group. “It's a low-engineering, low-infrastructure way to get across.” 

The team also hopes to preserve the educational aspect of Roy’s Redwoods by adopting a nature exploration area for kids. Here, they can use the forest’s natural resources to build forts, balance across fallen trees and play with sticks. 

The team surveyed 117 visitors, conducted bioblitzes and participated in community hikes to guide their restoration goals. “We learned about favorite trees, favorite spots, where kids build their forts,” said Claire Mooney, the senior director of projects and design for Golden Gate National Parks Conservancy. “We wanted to maintain that sense of wonder, discovery and wandering through the redwoods.” 

Next year, the design team plans to conduct an environmental review, finalizing its designs for implementation in 2021.