The purpose of this manual and accompanying field assessment form is to guide natural resource professionals in evaluating the described indicators of stream flow to help distinguish between ephemeral, intermittent and perennial streams. This method has been developed and tested for applicability across Oregon,from the humid west side of the Cascade Mountains to the semi-arid eastern two-thirds of the state. Section 1 contains an introduction to the method, including definitions of key terms, method development and validation, and sources of variability. Section 2 provides assessment guidance and describes the indicators. The final section describes how to draw conclusions based on the assessed indicators of flow.