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SELECTING LEAST-DISTURBED SURVEY SITES FOR GREAT PLAINS STREAMS AND RIVERS
Citation:
Whittier, T R. AND J L. Stoddard. SELECTING LEAST-DISTURBED SURVEY SITES FOR GREAT PLAINS STREAMS AND RIVERS. Presented at North American Benthological Society meeting, Vancouver, B.C, June 6-10, 2004.
Description:
True reference condition probably does not exist for streams in highly utilized regions such as the Great Plains. Selecting least-disturbed sites for large regions is confounded by the association between human uses and natural gradients, and by multiple kinds of disturbance. Using data from 112 randomly selected Environmental Monitoring and Assessment Program (EMAP) sites in the Plains, we defined a least-disturbed condition for each of four water chemistry, watershed, and site-scale indicators of disturbance. For each indicator, the definition of least-disturbed was adjusted for the site's location on the primary natural gradients. For example, the least-disturbed condition for phosphorus in eastern Plains streams allowed up to 100 micrograms/L total P, while in western sites < 30 micrograms/L total P was required. Sites were scored by the number of times they met the least-disturbed condition for the 12 disturbance indicators. We also applied this process to score for most-disturbed condition. Most sites in overall least-disturbed condition had 4 to 6 disturbance indicators that scored as least-disturbed with none in most-disturbed condition. For large rivers, we accepted sites with only three least-disturbed indicators. With this process, we selected 19 least-disturbed sites and 18 most-disturbed sites that were well distributed geographically, across the range of stream sizes.