A state board sliced more than 2,500 acres from Clark County commissioners' ambitious urban growth plan Thursday, upholding environmentalists' claims that it would pave over useful farmland.

Nine areas of agriculturally zoned land, including a huge industrial parcel south of Brush Prairie, won't be allowed to develop without further county action unless they've already been annexed by nearby cities.

The Western Washington Growth Management Hearings Board found that the county erred in allowing development on agricultural parcels outside Camas, La Center, Ridgefield, Vancouver and Washougal.

The proposed plan had been the biggest urban expansion on state records, according to the state's Department of Community, Trade and Economic Development, which had opposed the commissioners' decision.

The commissioners' plan had been appealed by Futurewise, a Seattle-based slow-growth group.

Rich Lowry, the county's top land-use lawyer, said Thursday that the county must now decide whether to look for more evidence to support its action, to amend its 2007 growth plan, or to appeal the ruling to a county superior court.

Lowry, 62, held a retirement party Tuesday and came to work Thursday hoping it'd be the last day of his career.

"It's not what I was hoping for," he said.