April BMP Q&A

By: Hughes Simpson, BMP Forester, Texas Forest Service 

Q:   I am planning on cutting a tract of timber in San Augustine County that has several streams running through it. I have heard about leaving Streamside Management Zones and want to follow the recommended guidelines, but don’t really know which streams need protection. Do all streams need protection? If not, how can I determine which ones should be protected?

A:   This is an excellent question. First of all, not all streams need protection. Streams are grouped into one of three categories (perennial, intermittent, or ephemeral), based on the amount of time during the year that water flows through them. An important thing to remember is that there are transition zones along streams where one category might be turning into another category. As you might guess, this classification can become very complex and challenging, especially during periods of heavy rainfall or extreme drought.

Streams are classified as perennial, intermittent, or ephemeral. Perennial and
intermittent streams require SMZ protection.

A perennial stream will flow at least 90% of the year and have a well defined channel. This channel will be sinuous (winding) and show evidence of soil and debris movement. Water pools are present, even during dry conditions. High water marks are sometimes noticed along the stream, as well as wetland vegetation, such as mosses, ferns, and some woody species. Gray soils with red specks are associated with these types of streams. The Texas Forest Service recommends leaving a minimum width of 50 feet on either side of perennial streams.

An intermittent stream will flow at least 30% of the year, usually during the wet winter months. This type of stream also has a well defined, sinuous channel that shows evidence of soil and debris movement. Water pools are absent during dry conditions but present during wet conditions. High water marks and wetland vegetation still occur along these areas. Predominately brown soils with gray soils mixed in are usually found here. The Texas Forest Service recommends leaving a minimum width of 50 feet on either side of intermittent streams.

An ephemeral stream will flow only during or after it rains. These streams are short lived, and don’t have a well defined channel. The flow area is almost always straight and there is an absence of water pools. High water marks and wetland vegetation are not found along these areas. Regular soils typical of the site occur around these streams. The Texas Forest Service recommends using your professional judgement in determining whether or not to leave an SMZ along ephemeral streams.

Remember, Streamside Management Zones can be managed to remove some of the economic value. These areas can be thinned to a minimum of 50% of the original crown cover or 50 square feet of basal area per acre. All logging debris should be removed from streams immediately to prevent any unnecessary blockage of the stream channel. If you have a question regarding BMPs, please call me at (936) 639-8180.

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