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<br />11 <br /> <br />perennial streams or those that develop a biota, precluding the UI;e of <br />mapping for classification (Hynes 1970). Therefore, data collect,~d from <br />mapping of different scales and indec~llion as to how 1:0 identify first <br />order strealllShave hindered the usefulne.. o,f the technique and created <br />confusion when attempting to compa~. data. <br /> <br />The Discharge/Watershed System <br /> <br />The need for information exchange and reliable data comparison on a <br />national and international basis requires consistency and uniformIty of <br />segment definition, map scale, and interpretation which does not !leem <br />possible with the stream order system. Moreover, even if all the problems <br />with definition and delineation were resolved, stream order would still be <br />an inadequate means of explaining or comparing the phy'sical and bIological <br />characteristics of streams (Hughes and Omernik 1981). <br /> <br />An alternative has been suggested to Eltream order' that has the <br />potential for broader and more useful appUcation, is more easily <br />delineated, and characterizes the sizes of '~atershed/s.tream systeals (Hughes <br />and Omernik 1981). The alternative system h based on. three streBem <br />discharge characteristics. In descending order of importance they are: <br />1. mean annual discharge per unit area, <br />2. mean annual discharge, <br />3. watershed area if definable (if not, the characteristics that <br />render it indefinable). <br />Mean annual discharge per unit area is a means of relating discharge to <br />basin area, thereby providing a means of comparing streams In different or <br />similar climatic and geologic regions (Hughes and Omernik 198 I). <br /> <br />An analysis of 6 fifth order streams plus a cursory examination of <br />several smaller streams across the country indicates the range and <br />variability in lIlElan annual discharge between different streams and <br />different sites on the same stream (Table 5 and Figure 6) (Hughes and <br />Omernik 1981). Based upon the assumption that stream order can be defined, <br />standardized, and obtained in a consistent manner, it '''as concluded that <br />important characteristics of watershed/stream systems show extreme <br />variability. The streams in the study were chosen bec..use they have a long <br />term record of (USGS) gaged discharge. The key findings of the comparison <br />include: (1) the mean annual discharge per unit area ,of the Siletz River <br />(an Oregon coastal stream) is 42 times greater than th..t of the Little <br />Snake River at Lily, Colorado, yet the watershed area ,of the Siletz is only <br />about 5 percent that of the Little Snake; (2) the watershed area of the <br />Little Snake River at Lily is 57 times greater than th,at of Willialnina <br />Creek, Oregon, yet the mean annual discharg,. per unit area of the T"ittle <br />Snake is only about 4 percent that of Wlll1amina Creek;, and (3) compared <br />with the Little Snake at Slater, Colorado, the Little Snake at Lily has a <br />mean annual discharge per unit area that is only 20 percent as great but a <br />watershed area and a mean annual diScharge that are 13 and 2.5 tim,.s <br />greater, respectively (Hughes and Omernik 1981). <br />