(Understanding Pennsylvania Trout Data)
Available as an advanced Web Map. Many of the underlying datasets may also be downloaded as KMZs via the PA Downloads Link in the Resources Menu!
The CH93 dataset is about 100MB, and was always too large for us to issue in KML format. With our advanced web-map technology, that’s no longer a problem: there’s a fully detailed CH93 layer now available on the PA web maps, which is zoomable down to about 1:35,000.
We’ve subtitled this article “Understanding PA Trout Data” because, when we saw this data mapped, it was one of those “aha” moments. It helped us realize that for a state as large as Pennsylvania, the trout data that we publish here is a “moving target”. The PA Fish and Boat Commission’s Strategic Plan for the Management of Trout Fisheries 2010-2014 noted:
Of the 64,345 streams totaling approximately 86,000 miles of flowing water in Pennsylvania, the PFBC has conducted surveys and/or implemented management on 4,877 streams totaling 24,959 miles. As a result, only 8% of the streams and 29% of the total stream miles are being actively managed. Of the waters yet to be surveyed, many likely support wild trout populations.
The scale of this issue is hinted at by the image below, which is from an earlier generation version of this same data. The red and orange areas are streams designated by the Department of Environmental Protection as “CWF”, i.e. Cold Water Fisheries (red) or “EV”, i.e. Exceptional Value (orange) – these correspond to the pink, blue, and purple areas in the web-map image above. Broadly speaking, almost all of the EV streams, and most of the CWF streams should support wild trout populations. These waters get classified as streams supporting trout reproduction when a PFBC survey shows that wild trout are present (blue). They can be further classified as “Class A” trout streams (bright green) if the data shows the trout “biomass” is sufficiently high (>40 Kg/Hectare, or >30 if brook trout dominate), AND if the PFBC commissioner certifies the stream as Class A.
Sources: PA Department of Environmental Protection, “Streams Chapter 93 Designated Use”, PFBC, and ESRI arcGIS Explorer
As the Strategic Plan points out:
At the time of the development of the stream classification system in 1983, there were 138 stream sections that had been documented to meet or exceed the Class A standards. This represented nearly 400 miles of stream. As more flowing waters were evaluated, the number of waters documented to meet the Class A designation expanded rapidly. By the end of 2008, 487 sections, representing 1,436 miles were managed as Class A wild trout waters. In the 25 years since the inception of the Class A wild trout program, an average of 41 miles of flowing waters have been added to the Class A program annually .
The reality is that there’s more wild trout water in PA than anyone knows about. A lot of it’s very marginal, but some of it is probably very good. In addition, at any given time, there are streams classified as “Class B” which should really be “Class A”, but where the bureaucratic wheels haven’t yet spun sufficiently to add the stream to the Class A list.