November 2013 BMP Q&A

       By: Todd Thomas, Water Resources Forester, Texas A&M Forest Service

Q:  While conducting a complete harvest on a site with dense underbrush, my crew accidentally cut through an area that should have been reserved as an SMZ.  Now that what’s done is done, what do you recommend as our next move?

A: While I hate to hear of the destruction of an SMZ, do not worry, not all is lost.  First things first, in order to eliminate any confusion during site prep and planting, the area that would have been SMZ needs to be flagged off.  This will avoid any intrusion of site prep or other management activities down the road that could cause any damage to water quality.

Aerial view of Streamside Management Zones (SMZs) on a recent harvest in East Texas

During site preparation and planting it is extremely important that any equipment on site stay out of the newly flagged off SMZ to avoid soil disturbance next to the stream.  This will reduce erosion and the resulting sediment that could enter the stream.  Remember, since you have harvested the timber off the tract, there will be more water wanting to enter the stream since those trees are no longer there to use it.  This means that there will be more water in the soil, especially right next to the stream, making the area much more prone to rutting.  If you do decide to plant this area when you are planting the rest of the tract, be sure and plant it by hand so you don’t rut up this sensitive area. 

Going ahead and marking off the area that would have been SMZ will also be extremely beneficial if you plan on using herbicides during site prep.  This will eliminate the possibility of any herbicide being directly applied to the stream.  Also, not spraying here will allow vegetation to re-establish itself quickly, and reduce erosion potential.  Not to mention this helps with maintaining biodiversity for wildlife habitat, one of the side benefits of SMZs. 

It may not be a bad idea to go ahead and plant a mix of hardwood seedlings in this area, just to ensure that things begin to reestablish at a rapid pace.  However, there is a good chance that there is enough seed already in the soil for seedlings and shrubs to grow in this area pretty densely.  I have heard stories relating to similar scenarios where hardwoods were planted, but were eventually out-competed by seedlings that grew from the already existing seed bank.  How you choose to approach this is totally up to your discretion. 

If you plant anything, it is probably a good idea to at least put down some grass seed.  There is chart that is extremely helpful in determining what to plant on page 67 and 68 of your blue book.  This form of revegetation will hold the soil in place while any seedlings are getting established.  Remember, per Texas BMPs, that it is not recommended to use fertilizer within an SMZ (page 66, blue book).  This is because excessive nutrients entering the stream can greatly degrade water quality. 

In conclusion, while it is never a good thing to slick off an SMZ, there are measures to restore the SMZ and to correct the mistake.  Remember to delineate the area, keep out equipment, and to actively manage the area to reestablish vegetation so that it can return to a functioning SMZ.  Keep the questions coming; you can call them in to me at 936-639-8180, or email me at tthomas@tfs.tamu.edu.

*This article was published in the November 2013 edition of the Texas Logger

September 2013 BMP Q&A

           By: Todd Thomas, Water Resources Forester, Texas A&M Forest Service

Q: My crew is in the middle of thinning a 15 year old pine plantation.  In the middle of the tract, leading down to an intermittent stream is an old legacy road that has washed out over time.  It is very apparent that the when all the timber was harvested over 15 years ago that no BMPs were used.  As this gully approaches the stream it gets deeper and deeper.  Where the gully meets the stream it is deep enough to swallow a pickup!  For the most part, the gully hasn’t eroded any more in quite some time.  There is little to no evidence of recent soil movement, and there is a pretty heavy layer of pine straw and other litter on top of the soil.  We have kept all our equipment out of the gully and haven’t cut any trees on the edge of the gully in order to keep things from washing out anymore than they already are.  What is our next move here?  How should we treat this highly eroded legacy road in future management operations? 

A: Excellent question, and one that addresses an issue that I am sure other folks are experiencing out there.  First and foremost, good job staying out of the gully and not harvesting the trees along the edge.  Even though the gully started out as a poorly placed road, it is now acting as an ephemeral drain and should be treated as such. 

The best way to keep this gully from eroding further is to keep equipment out entirely and to maintain a buffer of trees around the edge and above the head of the gully.  Now you may remember that Texas Forestry BMP guidelines do not require an SMZ on ephemeral drains, but depending on the situation, some protection is needed.  This is certainly a situation where some protection is needed.  The amount of protection, the width of the buffer, will depend on the soil type and topography of the site, based on your professional judgment. 

The buffer will accomplish several goals in the name of erosion prevention and protecting water quality.  The first goal is interception.  The canopy of the trees comprising the buffer will intercept rainfall and reduce the resulting soil movement from raindrop impact.  The second is root structure.  The roots of these trees will hold the soil in place, reducing the chance of the gully getting wider.  Since you are in the process of harvesting timber on site, the amount of water traveling to the gully is going to increase.  This surplus of water is a result of the harvested trees not being there to use it anymore.  The trees making up the buffer will intercept the bulk of this water, preventing further erosion. 

Maintaining a buffer also limits equipment intrusion.  Remember, since water is naturally draining towards the gully and in more abundance with less timber around to utilize it, the area around the gully is going to be much more prone to rutting.  Even in dry conditions it is important to minimize equipment operations immediately adjacent to the gully as this can cause soil disturbance that will eventually lead to further erosion issues. 

While it may seem like a good idea to place hay bales, slash, or silt fences in the gully, this should be avoided.  In a case such as this, where everything seems to have stabilized relatively well, putting something in the gully would likely cause further erosion on the side banks causing the gully to widen.  Placing hay bales or silt fences in the gully would not only enhance erosion, but also costs time and money.  Time and money that you could be devoting to other aspects of your operation, such as installing BMPs elsewhere!

In conclusion, an ephemeral drain is an ephemeral drain no matter how it started out.  No matter if a drain was put here by Mother Nature or the faults of man, at this point it deserves our protection.  Keep the questions coming, you can send them to me at tthomas@tfs.tamu.edu or call them in using the phone number 936-639-8180.  

*This article was published in the September 2013 edition of the Texas Logger