This Earthcache celebrates some key features of a section of this river. You will want to access the cache from a canoe or kayak. (Overland Access is mostly private property) I encourage you to paddle from Stones Bridge to Winneboujou for a wonderful experience and some light rapids.
This link gives a great paddle map, including rapid locations and difficulty.
The Bois Brule River Valley and the uppermost St. Croix River Valley were carved by meltwater flowing south from glacial Lake Superior and the surrounding uplands around 13,000 years ago. When the glaciers receded, a divide formed out of which the Brule and St. Croix rivers flow today in opposite directions. Much of the upper Brule is fed by coldwater springs which finds its way to Lake Superior along the old glacial melt flows.
From the Wisconsin DNR:
"A unique set of streams drain into the western-most region of Lake Superior along the central portion of Wisconsin's south shore. These streams extend from the Bois Brule River eastward around the Bayfield peninsula to the head of Chequamegon Bay. The most important of them include from west to east, the Brule, Flag, Cranberry, Bark, Pikes, Onion, Sioux, Whittlesey and the North Fish."
"Most streams around Lake Superior receive their base flow from areas with fairly shallow aquifers lying on bedrock; those mentioned above gather their cold groundwater flow from a unique geologic feature. This area consists of a large glacially deposited region of deep sands, some areas reaching several hundred feet deep. This area extends from the headwaters of the Bois Brule in a northeast direction through the center of the Bayfield Peninsula. Groundwater specialists have projected that rain falling on this landscape seeps quickly into the soils, then to be stored in the aquifer for up to a century, before emerging as springs near the headwater reaches of these streams. Cold, clean water creates a perfect incubating and growth environment for trout and salmon. Steelhead, brown trout, coho salmon and smaller numbers of brook trout, chinook and pink salmon depend on these "natural fish hatcheries" for spawning and juvenile rearing habitat. Trout and salmon require stable gravel and well oxygenated water to hatch their eggs during the long months of incubation. Most ascend the streams during fall to lay eggs in gravelly areas where they incubate in nests during the winter period and emerge in early spring. Steelhead, a spring-time spawner, deposit their eggs in spring where they lie until emergence in June. Once emerging, at less than an inch in size, they then spend from one to two summers growing in the stream environment before they migrate to the lake to continue their growth to adulthood."
This river is well known for great paddles, wonderful fishing, and quiet places to enjoy nature.
To receive credit for "finding" this Earthcache, please email me the answers to the following questions:
1. What is the unique geologic feature that allows for the coldwater flow and springs that feed the upper Brule River?
2. Describe the bottom of the river at the entrance to Big Lake and at the coordinates provided.
If you like, post a photo of your trip! I'd be happy to see some folks having a good time on such a geologically special and historic river!