Thursday, February 1, 2001

February BMP Q&A

By: Jake Donellan, BMP Forester (Ret.), Texas Forest Service

Q:   Due to the fact there were no questions this month, I would like to look in detail at some of the deficiencies noted in the latest round (Round 4) of BMP compliance monitoring.

A:   The report, “Voluntary Compliance with Forestry Best Management Practices in East Texas,” noted two major deficiencies during the evaluation of 150 forestry sites from June 3, 1998 to August 31, 1999. The first area of deficiency was sedimentation from stream crossings. The second area of concern was erosion problems from skid trails and temporary roads. This month lets look at the problem with stream crossings in closer detail.

Stream crossings can potentially contribute a large portion of sediment to a stream, thereby impacting water quality. This is one reason why we should really work hard to install them properly. The best stream crossing is one that never occurred. How can this happen? During the planning stage of your harvest operation, use tools like aerial photographs, topographical maps, and soil surveys in combination with field reconnaissance to determine site conditions.

By using these tools and getting out on the ground, you may be able to spot some backside access to the timber. Sometimes it is worth paying an adjoining landowner a couple hundred dollars to gain access than it is to build a crossing. If that is not possible, and many times it isn’t, then it becomes really important that you install your crossing properly so that you minimize the potential for sedimentation to occur.

There are a number of methods available to successfully cross streams and have little impact on water quality. You could try using a brush crossing or laying logs in the stream channel lengthwise. These types of crossings are very inexpensive and generally have a minimal impact on water quality as long as the material is removed promptly. Another alternative is temporary bridges like crossing mats or a bridge made of poles that can be loaded onto the truck later. When using culverts for permanent or temporary crossings, it is extremely important that they be properly sized. The culvert should be large enough to handle the stream’s maximum flow. They should also be maintained and kept free of debris. There is a culvert size chart located on page 50 in the Texas Forestry Best Management Practices – “Bluebook.”

Lastly, you should always cross streams at right angles and use of equipment in the streambed should be kept to an absolute minimum. It is also important that the approaches to the crossing be stabilized with appropriate structures. Stream crossings also require frequent inspections during operations to determine their functional and safe condition. When needed, corrective measures should be taken immediately to fully restore the crossing.

Next month if there are no questions we will look at how to improve on erosion problems from skid trails and temporary roads. If you do have a question regarding BMPs please contact me.

* This article was published in the February 2001 issue of the Texas Logger