The four-member crew was working on a documentary on the Nigerian oil industry and its affect on the national economy and environment when they were arrested, the Seattle Post-Intelligencer reported Monday.
Documentary director Sandy Cioffi said U.S. Sen. Maria Cantwell, D-Wash., with congressional colleagues and U.S. Embassy officials, persuaded Nigerian authorities to release the four Americans.
"In the darkest moments when it is easy to give up hope ... it's what got us through," Cioffi said.
The film crew said they were given inadequate food and water and were psychologically intimidated by their captors. They said they were not physically abused, however.
The Nigerian government had earlier said that they had gone into the Niger delta without the necessary permission and clearances.
Cantwell said her office is seeking a meeting with the assistant secretary of state for human rights to discuss the situation in the delta.
"We think something needs to be done to elevate the issues of human rights, corruption and environmental devastation," Cantwell said.