Chapter 1. Introduction
3
1.2
OVERVIEW OF THE CONCEPT OF "WATERS OF THE
UNITED STATES"
Methods for delineating WoUS in arid stream systems are required for estab-
lishing jurisdictional responsibilities under the Clean Water Act (33 U.S.C.
1344). In non-tidal waters lacking adjacent wetlands, Corps jurisdiction extends
to the "ordinary high water mark," which is defined in 33 CFR Part 328.3 as the
line on the shore established by the fluctuations of water and indicated by physi-
cal characteristics such as a clear, natural line impressed on the bank, shelving,
changes in the character of the soil, destruction of terrestrial vegetation, or the
presence of litter and debris. In practice the OHWM for a stream is usually
determined by examining recent physical evidence of surface flow in the stream
channel. In dryland fluvial systems typical of southwestern desert areas, the most
common physical characteristics indicating the OHWM include, but are not
limited to, a clear natural scour line impressed on the bank, recent bank erosion,
destruction of native terrestrial vegetation, and the presence of litter and debris
(COE South Pacific Division 2001). This approach to delineating WoUS is
different from the approach used to identify and delineate wetlands. In the case of
wetlands, there are criteria for hydrology, soils, and vegetation specified in a
national wetland delineation manual (Environmental Laboratory 1987 and subse-
quent guidance from COE Headquarters). In contrast, there is no hydrologic
definition of ordinary high water, and the identification of WoUS relies entirely
on physical features of streams.
Previous Page
