JEFFERSON CITY, Mo. -- The Missouri River was so low over the summer that barge traffic came to a halt on July 20, and did not resume until after Aug. 14, the Jefferson City News Tribune reported Saturday.

The U.S. Army Corps of Engineers wanted to release more water upstream, but were stymied by the U.S. Fish and Wildlife Service, which worried that the water would flood the eggs of two species of birds along the riverbank, Corps spokesman Paul Johnston said.

"We were told we were not authorized," Johnston said.

The eggs belonged to piping plovers and interior least terns, which had placed their nests close to the edge of the water, just south of the Gavins Point Dam in South Dakota.

The least tern is a small, gull-like bird listed on the federal endangered species list. Piping plovers are listed as threatened. Raising the river in July might have swamped 270 eggs or chicks.

Randy Asbury, executive director for the Coalition to Protect the Missouri River, said the closure marks the first time that the Endangered Species Act trumped river navigation.