Turning SF’s Great Highway Into a Park Will Have Major Ecological Benefits, Report Says

Supporters of San Francisco’s Proposition K, which would ban car traffic along the city’s oceanside Great Highway and turn the road into a park, say a new environmental report bolsters their argument.

Sea-level rise and coastal erosion already threaten the Great Highway, which frequently must be closed to clear windblown sand, and nonnative vegetation like ice plants abound. The report, released by the San Francisco Estuary Institute this week, recommends ways to reduce sand encroachment and promote biodiversity.

It lays out actions that could be taken under three scenarios: a full transformation of the Great Highway into a park, which Proposition K calls for; maintaining the status quo, in which the road is off limits to cars over the weekends; and bringing back full-time car access to the roadway.

“We were interested in particular because the future of this treasured space is so discussed, and right now, there are a lot of opportunities to support wildlife,” said Cate Jaffe, an associate environmental scientist at SFEI and one of the report’s authors.

Jaffe added that the Great Highway’s position between Ocean Beach, Lake Merced and Golden Gate Park, three of the city’s largest open spaces, makes it a critical connector for wildlife.

Several of the recommendations are possible regardless of Proposition K’s fate, including improving trash management and revegetating the area with native plants that both contribute to local biodiversity and reduce the amount of sand that gets blown inland.

Other recommendations, like planting large shrubs to encourage wildlife habitats or reducing street lights that are bothersome to wildlife, aren’t as practical unless the road becomes a pedestrian-only zone.

With Election Day just weeks away, proponents of Proposition K celebrated the report’s release as an affirmation of one of their chief arguments for the road’s conversion.

“The City’s major environmental groups join in the consensus that Proposition K will greatly benefit the Ocean Beach ecosystem and the wildlife that call it home,” wrote the Yes on K campaign in a statement.

“I think the report really makes clear that voters have a great opportunity to make a step forward for the environment,” said Peter Belden, political chair of the Sierra Club’s San Francisco group.

Belden noted other environmental concerns should the ballot measure fail, including ongoing pollution from car traffic.

“Anyone who’s looked at a supermarket parking lot … you often see this little dark spot where there’s a pool of the oil as some cars drip oil,” Belden said. “On the Great Highway, those liquids end up on the road, then wash into the ocean.”

Jaffe and the report both made clear that SFEI’s goal is not to advocate for a specific vote but to recommend ways to support the health of the ecosystem.

“We’re a nonadvocacy organization, so we’re trying to provide the best available independent science to inform ongoing planning efforts,” Jaffe said. “So even with cars, Great Highway could be made friendlier to wildlife.”

But even if the institute doesn’t take an official position, it seems the environment has a preference.

“While all planning scenarios for the Great Highway present some opportunities to enhance or protect ecosystem health, closing the roadway to cars entirely has the greatest and most immediate ecological benefits,” the report states.

Even if revegetation efforts succeeded in attracting more pollinator and bird species, the report notes that continued car traffic would have negative effects on wildlife, including “wildlife disorientation or avoidance behaviors caused by traffic, noise, and artificial light, in addition to wildlife-vehicle collisions.”

The No on Prop K campaign did not respond to a request for comment, but opponents of the ballot measure have previously argued that the Great Highway is a crucial transportation corridor for the city’s westside communities and that the harms of closing the roadway to cars outweigh any benefits.

Proposition K opponents have also warned that if the Great Highway were to close, traffic would be diverted to adjacent residential streets, increasing risk to pedestrians.