The Good, the Bad and the Beaver, by Paul Diprima
This article first appeared in the Rome News Tribune
Beavers are the largest rodents native to North America and have been around over seven million years in North America and even longer in Europe. Beavers are vegetarians living off of twigs, leaves and soft inner bark of deciduous trees as well as other plants.
Beavers are the only animals that modify their surroundings to help satisfy their needs by building dams that create wetlands and while doing so, protect their lodge. These dams form ponds and wetlands that both slow and store flood waters but also trap debris helping to keep manmade lakes from filling with sediment. Beaver ponds form habitats for other rodents, amphibians, birds, wetland plants and fish. I have always enjoyed fishing beaver ponds in Georgia and have caught a wide variety of warm water fish.
After many years the beaver ponds often fill with so much sediment and plant growth that they become open, wet meadows with a stream flowing through it. Over time the meadow may revert to a flat wooded area and become habitat for many other animals.
In a recent TU National on-line newsletter there was an article called “Be the Beaver” which detailed work that Lizzie Stifel participated in Northeast Oregon headwater tributaries, including streams in the North Fork John Day and Grande Ronde river basins. The work was with the U.S. Forest Service, the Bureau of Land Management, and Trout Unlimited. Lizzie is a TU intern.
The project was to place manmade structures that mimicked or resembled beaver dams across open meadows that have streams flowing thru them.
Quoting Lizzie from the article: “In Oregon, our crew forged this connection through a relatively new type of restoration tool: beaver dam analogues (BDAs). Water that backs up behind BDAs recharges the floodplain and increases the wetted width of the stream flow. Essentially, a BDA creates a porous wall of sticks, logs, and leaves that slows the flow of water in one part of the stream and retains much of this flow behind the “dam,” allowing some of this backed-up water to seep into the floodplain. This beaver-like engineering helps promote channel aggradation, or in other words, prevents channels from incising into themselves and away from the natural floodplain.”
The BDA’s that have been and are being built in Oregon and other areas with high altitude and that are located much farther north than Georgia have been very beneficial to trout giving the fish both places to live and to feed. Many areas of Oregon suffered from devastating forest fires of recent times. Again, Quoting Lizzie, “While many square miles of forests were devastated, after the burn, scientists discovered occasional patches of land that looked untouched in many cases due to beaver dams. Where many streams became troughs of black slush, the waters near beaver dams were clear and still harbored trout.”
Beavers are not always welcome in heavily populated areas and in close proximity to farms. Homes near beavers often lose favorite trees and shrubs. Smaller young trees are often first to go as well as things from the garden such as green beans, apples, potatoes, lettuce and broccoli. My friend Steve lives on the river complains of beavers every year.
Beavers in locations such as Oregon and northern areas such as Minnesota and Maine can be of great benefit to trout and other salmonids. In Georgia the beaver ponds on most streams help with flood and sediment control and provide great habitat for all types of sunfish and other warm water fish.
There are a few North Georgia trout streams that are negatively affected by natural beaver dams. Water can flow from springs at a temperature well suited for trout and get impounded by one or more beaver dams. With the trees often eaten by the beavers and no longer shading the creek, the sun warms these shallow pools. At each point where the water exits the pond the water flows from the top of the pool where it is warmest and after passing thru one or more ponds the water temperature can become fatal for trout.
Some of these spring fed streams warm so much that in late summer the water can become too warm for trout. The DNR monitors stream temperatures and will end stocking of the stream until the stream becomes cool enough for trout. To my knowledge all the streams that fall into this group are put and take streams without self sustaining trout populations.
You can form your own opinion about beavers. They do a great deal of good and sometimes even provide habitat for endangered species. Beavers can become a nuisance when their activities though good in some places become bad and unwanted such as in your back yard, farm, or your favorite put and take trout stream.
Paul is a member of Trout Unlimited, Coosa Valley Chapter