Environmental Protection Commissioner Bob Martin charged Thursday that the Corps violated a court order when it dumped sediments at a riverside disposal facility in New Jersey last month. A dike at the site later failed, and sediments were discharged into wetlands.
The Army Corps acknowledged dumping the river spoils in recently filed court documents.
Martin said he found out about the mishap this week.
"We will pursue every possible avenue - including legal steps - to make certain the Army Corps is held accountable for these failures," Martin said Thursday evening. "I am very concerned that the discharge may have had significant ecological impacts on wetlands or the river itself."
Army Corps spokesman Edward Voigt referred questions to the Department of Justice. A DOJ spokesman did not return an after-hours e-mail message for comment.
New Jersey has long opposed the Army Corps' plans to deepen 102 miles of the Delaware River's shipping channel because of concerns over the effect on water quality.
A federal judge allowed the project to begin in March, but limited construction and disposal to the state of Delaware. New Jersey charged Thursday that the corps violated a court order restricting the project from New Jersey.
A lawsuit to stop the project is pending.
New Jersey officials and environmentalists had angry words for the Corps after learning of the infraction.
"This situation is completely outrageous and typical of the Army Corps' attitude of barreling ahead with this ill-conceived deepening project with no regard for the environment or the significant questions raised by the State of New Jersey," Gov. Chris Christie said.
Maya van Rossum of the Delaware Riverkeeper accused the corps of "acting in bad faith," and Rep. Rob Andrews, who represents South Jersey, said he'll continue to oppose any federal funding for the project. So far, there has been none.
Despite New Jersey's objections, the Army Corps has begun deepening the river channel below Philadelphia from 40 feet to a depth of 45 feet. Proponents say the dredging will create jobs by boosting port business.