Photo: Nebraskaland Magazine, used with permission
The Nebraska Department of Environmental Quality designates 38 streams in the state as Class A Coldwater, defined as follows:
These waters provide a habitat which supports natural reproduction of a salmonid (trout) population. These waters also are capable of maintaining year-round populations of a variety of other coldwater fish and associated vertebrate and invertebrate organisms and plants.
All of the Class A streams are mapped in a KMZ included in the zip file. There you'll find both the KMZ and the 2012 source document. It provides some additional information about the streams, and a great deal of background (much of it quite technical) about the standards. If you click on the individual streams in Google Earth a balloon will pop up displaying data. The Subbasin and SegNum fields allow you to easily find the corresponding stream in Chapter 5 of this document.
As with all such datasets, the mere fact that a stream is capable of supporting salmonid reproduction doesn't mean that it actually holds trout. And (as I've discovered from extensive experience) even if a stream supports wild trout, it doesn't mean that they will be found in size and numbers sufficient to provide good fishing. Nevertheless, by definition, all of these streams are extraordinary in the context of Nebraska's environment, and all are worthy of our deepest respect. Sometimes it's enough just to see a trout in one of these exceptional streams.
Also, you'll find a beautifully presented summary of Nebraska trout fishing in the Zip file. It's a PDF reprint of an article from NEBRASKAland Magazine from Jan/Feb 2002. It provides photographs, maps, and access notes for most of the Class A trout streams you can find in the WildTroutStreams KML (Distributed with permission from OutdoorNebraska.org).