WI DNR defines 3 classes of trout streams as defined below the image. For the wild trout angler, the principal interest will be Class 1, shown in cyan. Each class of stream is provided in a separate KMZ file, which can be downloaded using the “Midwest Resources” menu in the sidebar.
High quality trout waters that have sufficient natural reproduction to sustain populations of wild trout, at or near carry capacity. Consequently, streams in this category require no stocking of hatchery trout. These streams or stream sections are often small and may contain small or slow-growing trout, especially in the headwaters. There are 5,400 miles of Class 1 trout streams in Wisconsin and they comprise 41% of Wisconsin’s total trout stream mileage.
Streams in this classification may have some natural reproduction, but not enough to utilize available food and space. Therefore, stocking is required to maintain a desirable sport fishery. These streams have good survival and carryover of adult trout, often producing some fish larger than average size. There are 5,911.6 miles of Class 2 trout streams in Wisconsin and they comprise 45% of Wisconsin’s total trout stream mileage.
These waters are marginal trout habitat with no natural reproduction occurring. They require annual stocking of trout to provide trout fishing. Generally, there is no carryover of trout from one year to the next. There are 1,864 miles of Class 3 trout streams in Wisconsin and they comprise 15% of Wisconsin’s total trout stream mileage.