They typically back up water when they are first built and mean lots of trout for the angler.
The WDNR shocked a huge brown out of this dam a couple years running. The land owner told me about the 29 incher he had on his wall that he discovered while he went along on a shocking trip. This stream had a thriving brook trout population but is protected these days due to gill lice. No brookies are allowed to be harvested due to the scourge that is gill lice.
The PH changes in long established dams and is typically detrimental to trout. Dams also block seasonal spawning. Dams are breeding grounds for gill lice. The biggest male small stream brown I have ever seen was caught behind this dam.
I caught 24 brookies at this dam and never moved from my casting spot. This is one of the streams that no longer supports brook trout due to gill lice.
The beavers have had this dam for 2 years now on the headwaters of one of my favorite streams. The spring that supplies the life to this stream is only 80 yards upstream of this massive beaver dam. The water spreading out over a larger area gives the water more surface area and warms the water way artificially and it could have long term detrimental effects on the trout population.
Dan Braun and I had a veritable field day behind this small dam slamming brown after brown.
Not a single trout was caught behind this warm stagnant dam this day.
Beaver dams long term are not an angler’s friend. Beaver runs can be way dangerous to step in and the pongee sticks the beavers leave behind can impale an angler.
Beaver dams are not good for the stream and you should contact the WDNR and tell them about dams you have found.
Gill lice thrive in beaver dams.
Please contact the WDNR when you find a beaver dam.
In the northern forested part of Wisconsin, the dams flood the forest kill the surrounding trees that haven’t been taken down by the beaver. Then the beaver ponds warms up and there is downstream thermal pollution. The dams block the upstream migration of spawning trout. Beaver are bad for trout streams.
“WDNR and USFS Fisheries Managers in Wisconsin generally agree upon the adverse affects which beaver dams create to the trout fishery. Many of Wisconsin’s 2,674 trout streams are located along low gradients and can be easily dammed. The average trout stream is 5 miles (Kmiotek 1980). Beaver dams on small trout streams usually produce effects which follow a definite pattern. First, the vegetation flooded by a new pond will decay, fertilizing the water and increasing the food supply. The trout then grow rapidly, and good fishing may result for a period of 1 to 3 years. If the pond area is shallow and exposed to the sun, it becomes warmer than the stream thereby favoring a great increase in minnow abundance. The minnows then eat much of the available food, reducing the production of trout. After a few years, the beaver pond may become quite shallow and warm because of silting, while decomposing organic deposits increase acidity of the water. Thus the pond and its outlet are likely to deteriorate in suitability for trout. Also, good spawning areas may be smothered by deposits of silt or physical barrier to upstream migration. In the long run, the damage to the trout and habitat may far outweigh the initial benefits, and it may take years before conditions improve, even if the beaver leave the area or are removed (Pasko 1969.”
