Thursday, August 1, 2002

August BMP Q&A

By: Hughes Simpson, BMP Forester, Texas Forest Service

Q:   A major perennial stream flows through our property and floods at least once a year. These high waters have blown out several culverts and caused severe erosion on the stream banks. Reinstalling another culvert is extremely expensive, so we have decided to retire this rarely used crossing. However, we still would like to stabilize the banks to keep them from washing into the stream. Is there an effective way to accomplish this?

A:   Stream crossings can be very expensive to install and maintain, and if they don’t function properly, can cause major impacts to water quality. These “contact points” are areas where soil can directly enter streams. Retiring old crossings that are not used and stabilizing their stream banks are excellent practices to reduce the potential severity of sedimentation problems.

Restored and seeded stream crossing
There are several effective ways that you can stabilize the stream banks of this crossing. Establishing a good vegetative cover on these erodible sites through seeding will help keep the bank intact and filter runoff water before it reaches the stream. Seed mixes should include a variety of grasses suited for the site conditions present to ensure a high survival rate. Planting in the spring or fall can greatly increase the success of this operation. Fertilizers should not be applied inside the Streamside Management Zone (SMZ) to prevent stream contamination.

Depending on the time of year and the site conditions, grasses may not always grow in these areas. Spreading hay along these banks can also provide erosion control. This method is extremely effective when it is done after seeding. As the hay decomposes, the grass seed begins to germinate and holds the soil in place. This material can be applied more efficiently and evenly distributed using hay blowers. Care should be taken to avoid hay from reaching the stream channel.

Another method that works well is installing rock along the slopes. Securing this material in place can provide great erosion protection and bank stability, however this procedure is generally more expensive than the above mentioned. It is also important to prevent rocks from entering the channel and impeding stream flow.

There are many other techniques that can be implemented to help with this problem, including geotextiles, bioengineering products, and other erosion control fabrics. More information can be found on the Texas Forest Service webpage under the BMP Product and Vendor Guide. If you have a question regarding BMPs, please call me at (936) 639-8180.

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