During the 1990s, the ODFW undertook a comprehensive program of stream surveys designed to establish the distribution of the principal fish species in the state, including trout and salmon. While these surveys are old, one would expect them to still provide useful information, especially for streams in wilderness areas or other places where habitat is intact, and we know of no comparably comprehensive data source which is more current.
In the dataset, each icon represents a survey of a particular stream, at a specific location, on a specific date. There are thousands of icons, more than it appears in this low resolution image, since icons are rendered on top of each other at this scale. Zoom into an area to see what’s going on more clearly.
We created a data field in the attribute table which is the total number of trout counted in the survey, adding together counts for rainbow, cutthroat, bull, brook, and brown trout. Icons are color coded for the number of trout counted: black means 0, and the lighter the icon, the higher the count. If you roll over an icon you’ll see the total trout count, and if you click on it you’ll pop up a balloon with the complete data record for that survey, which breaks out each trout species, plus multiple salmon species individually. (See image below)
Source: Oregon Department of Fish and Wildlife Aquatic Inventories Project 1990-2002 viewed in Google Earth. KMZ by WildTroutStreams.com