The Board of Supervisors unanimously denied an appeal, filed by the Salmon Protection and Watershed Network, of a proposed home in Woodacre that the nonprofit believes would harm fish and increase the likelihood of landslides.

Plans for the 1,900-square-foot home, garage and septic system—plagued by a decade of delays because of cracks in the adjacent road and a major landslide—met criticism at Tuesday’s hearing from SPAWN, the California Department of Fish and Wildlife and a neighbor concerned about slope stability and the durability of a county road repair from 2012, which is slowly being undermined by erosion. But supervisors were satisfied with county staffers, who say the project is safe.

“I think the issues related to the road are important, [as] part of our responsibility to maintain public roads. I hold that independent to the application for the individual residence upslope of that,” Supervisor Steve Kinsey said.

Despite the years that have passed since he first developed plans for the home, property owner Jim Murray said, “I still have a vision to build a house and to live in it.”

Mr. Murray originally submitted plans for at the site in 2004, but the effort stalled: major cracks were discovered in Redwood Drive, and in 2011, a landslide next to the property led to the road’s closure. The county repaired Redwood, but a subsequent moratorium on development in the valley, which ended in 2014, further delayed the project.

SPAWN, which filed the appeal after the Planning Commission approved the project in July, believes that a new home will exacerbate the slope’s instability and cause more sediment to flow into Woodacre Creek, citing the findings of a geotechnical advisor it hired to evaluate the plans.

A representative for SPAWN, Cassie Burdyshaw, said the group believed the project failed to comply with the California Environmental Quality Act. She also said the county had still not completed an amendment to its environmental impact report for the 2007 Countywide Plan, which a judge found in 2014 did not adequately evaluate the cumulative effects of development in the valley. Approving projects, she said, was “having a cumulative effect in the area.”

But the county points out that, despite the need for new analysis of cumulative impacts—which it says it in the works—the judge did not impose another moratorium on development in the area. The county says it is following the precepts of the 1994 Countywide Plan, as required by the court.

And in fact, the county believes the new home could make the slope safer, acting as a retaining wall of sorts.

Yet SPAWN is not the only one with concerns. A neighbor, Steve Morey, fears that a portion of the creek near the toe of the slope is eroding—and said a county civil engineer, Ernest Klock, told him he could be held accountable for related road damages because the erosion is happening on his property. But Mr. Morey blamed the problem on the county’s decision to undertake a less expensive repair to the road, which only addressed erosion on the county’s right of way. Without a better road repair, he worries that the new development could have ominous impacts to the slope. “It needs to be repaired properly. I urge you to look into this matter before you make a decision on this development,” he said.

The California Department of Fish and Wildlife also objected in a letter sent to the county on Aug. 19, a follow-up to an appearance at the Planning Commission hearing two months ago. 

In that letter, Gail Seymour, an environmental scientist, asked the county to delay approval of the project until it conducted a new geotechnical investigation of the property. She expressed specific concerns about the “sloughing and sagging” of Woodacre Creek’s lower bank, perhaps caused by a drain installed as part of the road repair (for which the county had to get a permit from fish and wildlife). She also said vegetation that the agency had required for the permit was not working. “To date, the majority of plants have died and therefore there is little or no erosion control in place,” Ms. Seymour wrote. She added that previous letters of concern she sent to the county on similar matters had never been answered.

But Mr. Klock, dismissed the idea that major erosion was a problem due to the county repair. “None of the work associated with our repair, within the limits of the [county’s] right-of-way, are failing into the creek…[Fish and wildlife is] not talking about our slope and our stability. They’re talking about unstable, unreinforced, unprotected erosion on private property,” he said. And even if some water were to be escaping from the drain, he added, it barely registered compared to the significant and natural flows during winter rains, which he said was the primary cause of erosion.

He did say that an area of the creek is slowly eroding and would “ultimately have an undermining effect to our road repair.” But he said the erosion is happening slowly and posed no “immediate threat,” so the Department of Public Works would only act when the erosion was “back on our property,” rather than on private land.