To clean up the lake, we must take care of the land. While this fact may seem counter intuitive, the green slime in Lakes Tainter and Menomin is a product of the ill health of the land. The most critical land is the riparian zone which is the land, and water on both sides of the shore of the streams, rivers and lakes. Or to use a modern term, it is the interface between land and water. Riparian areas are critical for most of the critters that live in the lakes and rivers at some point in their life cycle. Healthy riparian areas with lots of trees in the water produce clean lakes and lots of fish while unhealthy riparian areas produce siltation, fewer fish and lots of green algae.
A new program known as either Fish Sticks or Wood Drops which designed to improve riparian areas and help clean up the lakes is being implemented on Lakes Menomin and Tainter. The Dunn County Fish and Game Club is sponsoring the program, but the idea comes from Ma Nature herself. My many trips to places like the Boundary Waters confirms that the shores of healthy lakes are full of trees and wood. So why not add trees and wood to the shore of developed lakes to see if they improve water quality and habitat.
Scientists have studied the effect of wood in water and have found out some amazing facts. Up to 15 different species of fish may inhabit one submerged tree. One submerged white pine tree in Wisconsin harbored black crappie, smallmouth bass, largemouth bass, walleye, muskellunge, rock bass, bluegill, pumpkinseed, mottled sculpin, logperch, Johnny darter, yellow perch white sucker and minnows. The different species of fish use the trees in different ways. Smallmouth and largemouth bass will build their spawning nests near submerged trees. And Rock bass makes the nests under trees. These species of fish defend their nests so nesting nears underwater trees means less perimeter to defend. Smaller fish like blue gills use the submerged branches as cover while bigger fish like walleyes and northern lurk about the trees looking for a meal. Some types of minnows will actually spawn in the holes in the tree to protect their eggs. Other studies have shown that invertebrate species also thrive in the underwater woods. Turtles and birds use the emergent portion of the trees to roost and as a sunning station. Amphibians need the structures provided by submerged trees to lay their eggs. A lack of wood means the eggs will be concentrated in smaller areas and make the eggs more susceptible to predation. Studies show that lakes with fewer submerged trees have fewer amphibians. Birds like egrets and herons find the trees great places to catch supper.
In addition to providing a place for fish and other critters to live, trees have many other positive effects on lakes. The trees lessen the power of waves and of ice that impact the shore: Thus reducing erosion by these two forces. As a result plants are able to germinate and take root near the shore where there are submerged trees. The trees preventing erosions and allowing vegetation to grow on the shore has a multiplier effect for healthy lakes. The grasses filter out run off and reduce phosphorus entering the lake and the bugs that live in the grasses end up feeding the fish in the water.
Trees can last a very long time in the water. Some studies have found that white pines can last as long as 900 years under water! How long a tree lasts is dependent on the species of tree. Aspen has the shortest underwater life span while the eastern white pine can last up to 900 years. The more branches a trees has underwater the better the habitat it provides for more species of critters. However, as the tree begins to rot under water and loses its small branches it still provide good habitat for many critters and even some fish and invertebrates prefer to hang out in or near the trunk of the tree rather than in the branches.
If trees are so good for lakes and river why is there a dearth of trees in most of the lakes in Wisconsin? The answer is shore land development. Building that dream home on that dream lake shore is about the worst action that can be done to a lake. One study in Maine looked at two similar lakes; one that was undeveloped and one that had significant development. The study found a 720 percent increase in phosphorus runoff in the developed lake.
So what are “Wood Drops?” . I spoke with Richard Mechelke about a pilot wood drop program that was completed last year by the Dunn County Land Conservation Department at Menomin Park. He explained that Wood Drops are a method to reintroduce woody structures into developed lakes so that the woody structure will have a maximum habitat and water quality benefit. He also noted that habitat quality is as important as water quality in having a healthy lake. A highly eroded section of the lake bank was selected for the project. Mr. Mechelke noted that based on the number of old bricks found on the site, the erosion problems had been occurring for decades. The two keys to a successful Tree Drop are placing the tree in bunches and keeping the trees from floating away. C R Bryan & Sons Inc did the work on the project. Mr. praised CR Bryan for doing excellent work and for volunteering some of their time spent on the project in order to help meet the budget. Since there were no trees on the shore to use, the contractors got the trees from a nearby timber stand park. The trees were mostly pulled out by the roots. First trees were placed parallel to the shore right at the water line. Other trees were placed perpendicular to the shoreline so they extended into the lake. Some of the trees were placed in clumps and some were placed singly. About 5 to 6 feet of the logs that were perpendicular to the shoreline, were buried in the dirt to ensure they did not float away and to hold the rest of the wood in place. In areas where the trees line the shores, the trees are cut down into the water with a chain saw, and then the trunk of the tree is attached to the stump with a cable to keep it from being washed away by wind and waves.
I toured the site with Mr. Mechelke this summer and the changes are amazing. Soil erosion has been stopped, grasses and other plants are starting to take root in the once barren soil. I also observed minnows and other small fish swimming around the submerged wood. This demonstration project has been a major success.
The Tree Drop program has been successfully implemented on several other lakes in Northern Wisconsin. One of the benefits of the programs is to diversify and expand fish habitat in the lakes, which will spread out the fish population. Spreading out the fish population will also spread out fishing pressure in the lake since anglers will have more secret holes to find fish.