May BMP Q&A

By: Hughes Simpson, BMP Forester, Texas Forest Service

Q:   A network of drainage ditches and canals have been set up throughout the low lying areas of Southeast Texas to function in flood control. Normally, when I am harvesting a tract of timber that borders one of these structures, I protect this waterway with a Streamside Management Zone (SMZ). Recently, I have been asked by the Drainage District on any future harvests to cut up to the banks. This practice assists the district in maintaining these devices. Does this go against the state recommended Best Management Practices (BMPs)? Is there anything I should be aware of when carrying out their request?

A:   I am glad you asked this question. The flat topography that is typical of this area is also sometimes associated with soils that have poor drainage, causing water to pond. Drainage ditches and canals are important tools that can reduce the potential threat from flooding in Southeast Texas. Without these structures, millions of dollars in financial losses could be expected from frequent rain events. Can you imagine the impact Tropical Storm Allison would have had if these devices were not installed?

The Texas Forestry Best Management Practices Bluebook states that “SMZs for man-made drainage ditches should be established if appropriate”. You are to be commended for doing this on your previous harvests. These areas are a little different from springs, creeks, rivers, and other waterbodies in the fact that they are not naturally occurring and their primary use is for flood control. The main objective of BMPs is to protect water quality, so this should always be a consideration when working adjacent to these areas.

After discussing this issue with the drainage district, I understand their reasoning. Sometimes when timber is left along the banks, falling trees or limbs can impede water flow. When this happens, a greater impact to water quality can occur. Removing this debris is very costly and labor intensive, and also slows the implementation of the district’s BMPs. These guidelines, approved by the EPA and TNRCC, require them to re-slope their structures and provide plantings and mulch cover to prevent erosion and stream degradation.

Cutting all the way up to the banks at the request of the drainage district on man-made drainage structures would not be against the voluntary state BMPs. However, certain practices should be followed when conducting forestry activities adjacent to these ditches and canals. It is important that logging and site preparation debris is kept out of these devices and that soil disturbance is minimized in these areas. Bedding operations and other activities should not channel runoff water into these waterways. All herbicide and fertilizer applications should ensure that chemicals remain on site and out of waterbodies. Canal crossings should be avoided unless they are critical and can be installed properly.

This practice should only be conducted on man-made drainage structures and at the request of the local drainage district. Coordination with the district on the timing of harvest and re-sloping of the ditches or canals is crucial. Water quality can be impacted if there is a long time period between these activities. If you have a question regarding BMPs, please call me at (936) 639-8180.

* This article was published in the May 2002 issue of the Texas Logger