This pristine stream is near the upper end of the Passaic River flowing through Basking Ridge NJ. The source in Mendham flows into the remnant of a glacial lake which has devolved into the Great Swamp in Somerset County and wetlands through its central corridor.. The river meanders its way through and touches on Somerset, Union, Essex, Passaic and Bergen Counties to eventually empty into Newark Bay and the Hudson River. The lower Passaic has been heavily damaged by industrialization and pollution for more than a century but is slowly recovering through the efforts of both private and public resources. See here for more info.