SonOfMartin
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Breeches Dam Removal
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tomgamber
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It can only improve. lower water temps...less siltation...dams are bad...
There is going to be terrible bank erosion. I have been doing research at Franklin & Marshall College for the past two years that focuses on sedimentation due to the removal of colonial mill dams. Across the state thousands of dams were built and stored trillions of tons of sediment that erode off the hillslopes during colonial land clearing. Breeching these dams results in massive erosion of the unstable sediments trapped upstream. Eventually the stream will cut down to gravel and then begin to widen. The stream will become shallow and thus raise temperatures once it become too wide. In my opinion, dams should only be removed in conjunction with restoration projects. Otherwise, nothing is ultimately gained. Furthermore, most of our "prestine" restored trout water has been restored in an inefficient matter. The solution is returning the streams to what they were prior to European arrival. For more information go to www.landstudies.com. They are the only restoration company that currently does restoration with the attempt to return streams to natural conditions. Not to be offensive, but I feel that many conservation groups are wasting their money by designing our streams to function like western streams. Anyway, these are my thoughts on the removal of the dam.
Acristickid
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I am not educated what so ever in Geology/Engineering.
Is the effort to really return the stream/rivers to the way they were before europeans came? I do not think that is possible due to all of the development that has taken place since.
Moreover; I personally am more intersted in making the water better for the fish and ie fishing.
Is the effort to really return the stream/rivers to the way they were before europeans came? I do not think that is possible due to all of the development that has taken place since.
Moreover; I personally am more intersted in making the water better for the fish and ie fishing.
Padraic
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I'm not sure I follow your reasoning on how removing the dam will widen the stream. The dam is widening the stream now, removing it will allow the stream to cut to it's natural channel.
I have a friend who does this work professionally, and the permitting process requires the company removing the dam to have sediment management plan.
I believe you are correct that if may be impossible to know where the natural channel will be (or was) without the dam. However, being somewhat familiar with the area of the stream, I am glad to hear of the removal. The dam currently serves little purpose. The misquitoes will have to find new places to lay eggs, but other than that things should look up. The water behind that dam is almost still. The temps in the stream below the dam will definately improve.
I have a friend who does this work professionally, and the permitting process requires the company removing the dam to have sediment management plan.
I believe you are correct that if may be impossible to know where the natural channel will be (or was) without the dam. However, being somewhat familiar with the area of the stream, I am glad to hear of the removal. The dam currently serves little purpose. The misquitoes will have to find new places to lay eggs, but other than that things should look up. The water behind that dam is almost still. The temps in the stream below the dam will definately improve.
One huge problem associated with dam removals in that it is often difficult or impossible to get riparian vegetation to grow once erosion begins. The reason for this is very logical. Most "floodplains" are actually terraces of sediment that was stored behind the dam. The top of these terraces can be anywhere from 2 to 20 feet above the stream bed once the stream cuts down. While the stream water will eventually reach groundwater and thus result in lower temperatures, vegetation planted during restoration and for silt control often dies because it does not contact the ground water source. The reason the stream will widen is because the banks are much lower prior to dam removal than they will be a few years afterwards. Once the stream cuts down, the water velocity will be greatly increases during storm events. Beforehand the water was able to spread out on top of the sediment terrace hence lowering the velocity; however, the bulk of the flow will be restricted within the high-banked channels. The system will naturally fix itself by widening over time; however, gravels and bedrock may be eroded in the process. I do agree that removal of valley bottom sediment is not practical in all situations; however it should also be noted that while most of the regional streams were actually wetlands and branching-channel systems, they sustained great populations of salmon, trout, pearch, shad, etc. We know this from historical records and research is beginning to show that the functioning systems were nothing like they are today. Keep in mind that our research has been primarily in the Piedmont; however, streams in the Ridge and Valley and the Plateau experienced similar phenomena. I want to emphasize that I am not trained in geology/engineering. Instead, I am trained in neuroscience and currently applying to medical school. The research I previously discussed is both new and very important. I have done this research solely because of my passion for trout fishing and conservation. If you don't believe my hypothesis about the Breeches dam removal that is fine; however, please remember this post 5-10 years after the dam is removed. You may then find answers to some of your questions. Lastly, thank you to those who have sent me messages regarding interest in the research being done. It is much appreciated and also rewarding to know that some are beginning to understand this new approach to restoration.
I don't think I mentioned this yet but I am surely in favor of dam removal; however, from the few that I have seen, the siltation prevention has been sub-par. While you can't do anything about that, you can remove the source of future siltation once the dam is gone.
Dams are going to come down because of economic reasons regardless of the environmental effects. Most dams have outlived their economic purpose and the current owners probably can't pay for dam upgrades when they require it. Dams have finite lives too. Most dams around me seem to be 1920's upgrades of earlier dams - very few are the colonial originals. In the 80 years since these dams were built the mills they once powered are shuttered and the dams are getting a little creaky. Since it is cheaper to tear them down than restore them, most owners will take the path of least cost and tear them down.
Since it is inevitable, the environmental effects of these early teardowns must be carefully studied. More dam removals are on the way and we must learn to do it right.
Since it is inevitable, the environmental effects of these early teardowns must be carefully studied. More dam removals are on the way and we must learn to do it right.
The main thing is they have to WANT to do it right and be willing to pay what it takes to do it right.
The knowledge is already available on how to do floodplain and stream restoration. The problem is that it's expensive and they are currently not willing to spend the money to do it right.
