This year, for a change, the calendar and the weather agree that it is spring. The grass is starting to get green in places and we are having a few warm days followed by a day or two of snow. Spring is supposed to be the season of change, not just cold and snowy. The wildlife in the area are also showing signs of spring. Geese on the lake are swimming around in pairs, looking for a good place to nest. Bluebirds are checking hollow trees and the houses we have put out for them. In the evening, we can hear the call of the wood ducks in the timber near the far end of the lake. We have also noticed an increase activity from our resident beavers.
Beavers are fascinating creatures. When we first built our lake, I thought it would be fun to have a pair of beavers to watch. At the time, Iowa State University had a pair of beavers move into a small pond in the center of campus. They were becoming destructive by removing the ornamental trees in the area so the Department of Natural Resources was asked to re-locate them. I contacted the DNR and offered a home for them, but never heard back. They must have found a home closer Ames. A few years passed and one day I noticed some trees near the lake being felled by beavers. I excitedly told my wife we had new residents. A week or two later, I noticed the lake level had increased by more than a foot.
Our lake is fed by three creeks and the outflow is through a 36” concrete tube through the dam. I checked the tube to find dozens of pieces of wood neatly arranged and packed with mud almost totally blocking the outflow of water. It is no small job to dislodge the carefully constructed plug in the tube. When all their building materials a freed up and sent through the tube and downstream, the beavers have to cut all new building materials and start over. This takes them about a week. After several times of fighting to remove their plug in my tube, I decided beavers were not as interesting as I first thought. They were cutting down every oak and hickory tree near the lake, leaving behind any osage orange or thorny locusts. I finally gave up and had them trapped and removed.
Things went along smoothly, even when I noticed new beavers moved in last fall. They were mostly cutting down willow trees, which was fine with me. They built a den at one end of the island and moved tons of willow trees to their site to use for winter food and building materials. They left the outlet tube alone and all was well.
When most of the ice and snow melted on our warm days, the lake level rose as it normally does. In two or three days, the lake level usually drops back down to normal level as excess water is drained off through the large concrete tube. After a week or so, the water had not gone down and may have even risen more than when the snow first melted. I stopped by and checked the tube one day on our journeys and discovered the tube was plugged. Many small logs, sharpened on both ends, were lodged in the tube and the neat framework was sealed with mud.
I realize it is spring and the beavers are afraid all their water is going to go out of that tube if they do not plug it up, but I am getting tired of undoing their work. They need to get about their other springtime activities and leave the lake level where it is or they will be forced to find a new home.