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<br />Use in Ecosystem Management and Restoration <br /> <br />The Clean Water Act Amendments of 1972 (PL 92-500) called for the restoration and <br /> <br />maintenance of the 'chemical, physical, and biological integrity of the nation's waters.' <br /> <br />Increased use of analytical methods such as the Indicators of Hydrologic Alteration will , <br /> <br />demonstrate just how far we have to go toward restoring the physical integrity of our nation's <br /> <br />rivers, lakes, and aquifers. We anticipate that the IHA method will be used in conjunction~,~, <br /> <br /> <br />with other ecosystem;metrics .which. more directly. evaluate the biological conditions amL'''4iol.' <br /> <br />ecological degradation within an ecosystem, such as the Index of Biotic Integrity (KarrW~ <br /> <br />1993). Other authors (e.g., Karr 1991, 1993; Keddy et al. 1993; Minshall 1993) have~.,. <br />. . ,--" .... ~} <br /> <br />emphasized the importance of using a multi-parameter suite of metrics to assess ecosyste% '\:' <br /> <br />. - , ~., <br />integrity, since it is unlikely that anyone metric will have sufficient sensitivity to be,,~e~)oi{ <br /> <br />under all circumstances. <br /> <br />.."hm/)' <br /> <br />As illustrated by the case studies, the IRA method is extremely useful in drawing. , <br /> <br />attention to aspects of a hydrologic regime which are altered by various types of human <br /> <br />influences such as.dams and"ground,water'pumping.;cHowever, elucidation of hydrologi,c <br /> <br />alterations ,alone tells us littie about the nature or degree to which biologic patterns and <br /> <br />A;~~tij- <br /> <br />processes may have been degraded in response to such alterations. The tough work of <br /> <br />,-flfJO~_.- <br /> <br />interpreting and documenting species- or community-specific responses to hydrologic c~~. <br />remains. We feel that by revealing the direction and magnitude of hydrologic alterations, \!,1e;' <br />. . " _' .". .~~- 1'7; <br /> <br />~. . 'h <br /> <br />IHA will aid ecological researchers in formulating hypotheses about the hydrologic causes of <br /> <br />various forms of ecosystem degradation. For example, the lHA results for the Roanoke River <br /> <br />suggest that impacts to the littoral zone benthic fauna should be assessed; in the Edwards <br /> <br />24 <br />