An environmental group filed an appeal Tuesday with the Napa County Board of Supervisors over a controversial vineyard conversion project that is backed by a prominent and politically connected wine family.

The Oakland-based Center for Biological Diversity has contested the Aug. 1 approval of the Walt Ranch project by David Morrison, director of Napa County’s Planning, Building and Environmental Services Department.

The proposed ranch is located between the city of Napa and Lake Berryessa and is one of the most ambitious vineyard conversions on the North Coast. It is backed by Craig and Kathryn Hall, owners of the Hall and Walt wine labels. Kathryn Hall served as U.S. ambassador to Austria during the Clinton administration, and the couple have bundled more than $191,000 for Hillary Clinton for her 2016 presidential campaign, according to the Center for Responsive Politics.

In response to environmental concerns, Morrison curbed the original proposed 507-acre development to protect trees and wildlife and require a revised erosion control plan. The project would be located on approximately 2,300 acres.

As approved, the project would have 209 acres of new vineyards within a 316-acre impact area. The new vineyards are significant, given that Napa County vineyard acreage has remained relatively static for the past decade, at 45,537 acres last year.

The changes approved by Morrison, however, did not quell opposition by community activists who have opposed the project for the last 10 years, contending it would harm the watershed and cut down too many trees.

The center argues the project would destroy habitat for the threatened California red-legged frog, valley elderberry longhorn beetle and the endangered Contra Costa goldfields.

“We acknowledge the changes to the project. But it’s not enough,” said Aruna Prabhala, a staff attorney with the center.

She added the ranch is “home to a vibrant wildlife community and contains some of the most important oak and riparian habitat in Napa County. We can’t let this proposed vineyard cut a jagged hole right into the heart of it.”

The center said the project violates the California Environmental Quality Act and that there was inadequate review of the proposed vineyard’s impact to wildlife, water supply and air quality.

Mike Reynolds, president of Hall Wines, said the vineyard project has undergone the most thorough environmental review in Napa County’s history and that such concerns have been addressed in Morrison’s final report.

“We are planting a vineyard in an area where it is an agriculture zone,” Reynolds said. “This is the best use of the land.”

He noted that only vineyards would be constructed on the property ­­— no wine-processing facility nor tasting room — and its footprint represents only 8 percent of the overall property. “It’s a small part of a really big property,” Reynolds said.

You can reach Staff Writer Bill Swindell at 707-521-5223 or On Twitter @BillSwindell.