Friday, May 4, 2012

May 2012 BMP Q&A

By: Todd Thomas, Water Resources Forester, Texas Forest Service

Q: Recently we were doing some work on a tract that had a pond in the middle of it and just to be safe we left a buffer of trees around the pond. I understand that we are to leave an SMZ on perennial and intermittent streams as well as on ephemeral streams depending on site conditions; but what about ponds and why?
A: If the pond is connected to an intermittent or perennial stream, then leaving an SMZ is recommended. Professional judgment, just like with ephemeral streams, can be used on disconnected ponds. Certainly leaving a buffer around a pond is beneficial, and can help maintain high water quality as well as extend the lifespan of the pond.

First and foremost, the SMZ slows down runoff from the surrounding areas. Without this buffer, runoff water would continually gain speed as it headed towards the pond giving it the power to erode the surrounding soil and carry it into the water. Not only does this buffer slow down runoff, but the remaining vegetation intercepts rainfall. It’s hard to believe, but the impact of a raindrop can greatly displace soil. Instead of a direct hit, the trees catch the rain and slow it down so that its impact and resulting erosion is greatly reduced.

Increased sediment from erosion can eventually silt in a pond, but aside from this there is another reason to leave some of the surrounding trees. In all likelihood, trees have grown up on the dam. These trees should be left there or you risk weakening the dam and potentially losing the pond all together. Once these trees are removed, the roots and stumps rot out and an empty space is left there, weakening the structural integrity of the dam, and increasing the risk of the dam collapsing. Not only could you lose the pond, but the water from the dam breaking could cause massive erosion, making the other BMPs you implemented on the tract pointless.

Lastly, SMZs provide shade to the pond’s edge, helping keep the water in the more shallow areas cool. This is especially important for aquatic life such as small insects and fish, which often serve as food for the larger fish in the pond.

Next time you stumble across a pond or lake on a tract remember, that if it is part of a stream system, be sure to leave an SMZ. If it is not, consider the benefits of leaving a buffer if you deem it necessary.

Before I wrap this up, I want to take a moment and mention that the Texas Forest Service Water Resources Program has recently released a new online “blog” on which we will be discussing and highlighting current BMP and water related issues. The blog also contains all of our past BMP Q&A articles dating back to 2000! You can search through the articles by date or keyword and add your own thoughts and experiences by commenting on the posts. The blog is located at I would encourage you to stay up to date with the latest BMP news and information by checking it often. Be sure to tell your friends about this new resource as well.

In addition to the blog, there is a wealth of BMP information on the Texas Forest Service website at If you have any questions you would like answered or to see in this article, please send them my way, you can contact me by phone at (936) 639-8180 or email at

 *This article was published in the May 2012 issue of the Texas Logger

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