Also Tuesday, activists have called for demonstrators to protest at Army Corps of Engineers offices and offices of banks that are financing the pipeline project. The protesters want President Barack Obama to permanently halt the construction of the $3.8 billion pipeline.
Kennedy is an environmental attorney and president of the New York-based Waterkeeper Alliance, which seeks to protect watersheds worldwide.
The pipeline is to run beneath a Missouri River reservoir in North Dakota that provides drinking water to the Standing Rock Sioux tribe, which says the pipeline threatens drinking water and cultural sites.
The pipeline would deliver oil from North Dakota through South Dakota and Iowa to a shipping point in Illinois.
Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.