Environmental groups are suing to block a 52-mile highway that would complete a perimeter road around metro Birmingham.
The Southern Environmental Law Center filed the federal lawsuit Friday on behalf of Black Warrior Riverkeeper.
The suit contends the U.S. Army Corps of Engineers failed to follow the Clean Water Act and other laws when it approved permits for the first construction phase of the so-called Northern Beltline.
The long-delayed road would connect with Interstate 459 and Interstate 59 to complete a highway perimeter road around Alabama's largest metropolitan area.
But environmental groups say the project would damage rivers, streams and wetlands along the highway's path in Jefferson County.
The Corps of Engineers didn't have any immediate comment on the suit.
Another lawsuit over the project was filed two years ago.