CARY — Four western Wake County towns are a step closer to building a regional wastewater treatment plant in New Hill, an unincorporated community in southwest Wake County that has fought the plant for years.

The U.S. Army Corps of Engineers gave its final environmental approval for the site today.

The so-called record of decision — an 85-page document that outlines the possible environmental impacts of the project — paves the way for a building permit. If approved quickly, the $327 million plant could be built by the end of 2013.

Cary, Apex, Morrisville, and Holly Springs formed the Western Wake Partners in 2004 to begin planning a wastewater facility that would help them comply with a state environmental mandate, directed primarily at Cary, Apex, and Morrisville, to return water to the Cape Fear River Basin and to keep pace with the towns' rapidly-growing populations.

Many New Hill residents have opposed the plan. The opposition was among the reasons the project has been delayed for more than three years.

Residents had hoped to persuade regulators to strike down the New Hill location altogether, claiming it unnecessarily burdens the mostly minority, low-income residents at this crossroads near the Shearon Harris Nuclear Power Plant.