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<br />-., <br /> <br />29 <br /> <br />areas to the warmer downstream reaches is generally followed by a <br />progressive increase in the nu.ber of sped.es and a disappearance of some <br />species normally found in cold water (Shelford 1911, Ricker 1934, Kuehne <br />1962, Panitz 1964, Whiteside and McNatt 1972, Platts 1979). Streams with <br />summer temperatures exceeding 20 C generally contain 'Jarmwater fish species <br />and those ranging below 20 C generally are restricted to coldwater <br />species. Because some species have a ",ide temperatur,. tolerance and can <br />survive above and below 20 C they have been termed soldwater species. <br /> <br />Coldwater/Warmwater Stream Habitat <br /> <br />The total amount of warmwater and coldwater habitat for the <br />conterminous 48 states was determined from a computer gellerated map based <br />on climatic temperature regime (Schuder 1981). Planimetric analysis of the <br />map indicated that of the total sqllare mil,~s (3,615,l:t3) of land surface <br />(excluding Alaska and Hawaii) approximately 2,241,376 square IIlile.. or 62 <br />percent of the total landscape contains wal~mwater habUat and thalt: the <br />remaining 1,373,747 square miles or 38 per'~ent contains coldwater habitat <br />(Zilis 1979). <br /> <br />Data in Table 7 are based on the estimated total stream milage in the <br />48 conterminous states (Leopold et al. 1966) and the percentage of the <br />landscape that contains warmwater (62 perCE!nt) and coldwater (38 percent) <br />stream habitat (Zilis 1979). WaI1lll<ater and coldwater stream milage ",as <br />computed for small (orders 1, 2, 3), mediu" (orders 4 ,. 5. 6), and large <br />(orders 7-12) size stream order groupings based on thE' Law of StrE!am <br />Numbers and the percent of total stream milage in each stream ord.!r <br />grouping was determined. The values are based on the assumption l:hat all <br />sizes of warm and cold streams are more or less equally distributE!d across <br />the landscape (which may not be valid). HCl!Jever, even if the margin of <br />error in the analysis is large the comparisons serve to illustratE' the <br />significant differences between the small, medium, and! large stre<Lm order <br />groupings and the 24 percent difference in the amount of warmwater and <br />coldwater habitat. Similar analyses were ..~de for the, state of Colorado <br />and a group of several western states (Table 8) (Windell 1980). <br />