The following excerpt from the NPS, NRI website describes the eligibility for a river to be listed-
In order to be listed on the NRI, a river must be free-flowing and possess one or more Outstandingly Remarkable Values (ORVs). Thus, the eligibility analysis consists of an examination of the river's hydrology, including any man-made alterations, and an inventory of its natural, cultural, and recreational resources. There are a variety of methods to determine whether certain resources are so unique, rare or exemplary as to make them outstandingly remarkable. The determination that a river area contains ORVs is a professional judgment on the part of the interdisciplinary study team (IDT), based on objective, scientific analysis. Input from organizations and individuals familiar with specific river resources should be sought and documented as part of the process. In order to be assessed as outstandingly remarkable, a river-related value must be a unique, rare, or exemplary feature that is significant at a comparative regional or national scale. Dictionary definitions of the words "unique" and "rare" indicate that such a value would be one that is conspicuous example from among a number of similar values that are themselves uncommon or extraordinary. Only one such value is needed for eligibility.”
This data set was obtained by Bernardin, Lochmueller & Associates, Inc., using data believed to be accurate; however, a degree of error is inherent in all data. This product is distributed "AS-IS" without warranties of any kind, either expressed or implied, including but not limited to warranties of suitability of a particular purpose or use. No attempt has been made in either the designed format or production of these data to define the limits or jurisdiction of any federal, state, or local government. These data are intended for use only at the published scale or smaller and are for reference purposes only. They are not to be construed as a legal document or survey instrument. A detailed on-the-ground survey and historical analysis of a single site may differ from this data.
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