Updated 1/2014. Click on the >>>PA Downloads Link in the Resources Menu to download this KMZ for free!
Note: In 12/2013 we published kmz that extracts the Class B streams based on our analysis of the information described below. If you’re interested in Class B-D streams you will certainly want to download the Class B Streams KMZ as well as the overlay described here.
PFBC publishes detailed lists and vector datasets of wild trout and “Class A” streams. But of Classes B, C, and D there is barely a mention, except in passing. Based on the published lists, you don’t know how most of the “Trout Natural Reproduction” streams are classified, just the few in Class A. You have to look hard even to find out how the different classes are defined.
Turns out it’s all based on trout “biomass”:
- Class A streams contain more than 40 kg/hecatre* of trout if it’s dominated by brown trout or rainbows, or more than 30 kg/hectare if dominated by brook trout.
- Class B contain less than the 40/30 of a Class A, but more than 20. Class B also becomes the “Class A” in waiting, since it can take a while for a stream to be certified Class A.
- Class C have less than 20 and more than 10.
- Class D have wild trout populations, but somewhere between 0 and 10kg/hectare.
- Class E are cold water streams that have no wild trout, but are suitable for stocking
While PFBC is mysterious about the class designation of specific, listed streams, in its 2010-2014 Strategic Plan it published a small map (a jpeg of only 855 pixels across the entire state of PA and 455 tall) showing these class B-C-D waters. This map had been rendered on a GIS system of some sort, though using a projection not readily compatible with Google Earth’s. However, in 2014, using our nifty new QGIS workstation, we were able to geo-register and reproject the image so the geo-alignment is nearly perfect.
Moreover, the results are suprisingly useful. You can see a state-wide image here. Blue lines are Class B, green are Class C, and brown (the majority) are Class E.
The overlay becomes truly useful when you zoom in and view the stream datasets on top it. In the image below, we see a detail from Elk County. The overlay is the background showing B streams (blue), C streams (green) and D streams (orange/brown). The pink/red lines above the overlay are all rendered by the KMZ containing the PFBC’s “Trout Natural Reproduction” vector dataset which we’ve enhanced to provide CH93 quality ratings. The thick, light pink lines are rated EV; the medium thickness, dark pink lines are rated HQ, and the thin red lines are CWF. The Cyan lines are Class A streams, rendered by the Class A dataset. Note they miss the colored background entirely, which is appropriate. Our judgement of the class of the streams is shown with the yellow letters which we added in Photoshop. Given the tight geo-registration of the overlay, it’s generally clear cut what class any given stream is…
*For those of you not raised on the Metric system, a kg is 2.2 pounds and a hectare is 2.4 acres. So you can take the biomass numbers, add 10%, and convert it to pounds/acre. Or just use the numbers as they are (10% is no doubt within the margin of error).