Which of the following is NOT a feature of TRMs?

The correct answer is linked to the understanding of what TRMs (Turf Reinforcement Mats) are and how they function. TRMs are designed primarily to provide erosion control in areas subject to concentrated flows, often in short-term applications due to their temporary nature, typically intended to enhance vegetation establishment and help protect soil until more permanent solutions can be implemented.

However, they can also be composed of synthetic materials, which contribute to their durability and effectiveness in managing erosion in various environments. It's important to note that while TRMs are indeed used in concentrated flow areas and can consist of both natural and synthetic materials, they are not meant to function as permanent Best Management Practices (BMPs). Their primary purpose is often to stabilize soil during the establishment of vegetation rather than to provide long-term, permanent erosion control solutions. Therefore, identifying that TRMs are inherently temporary in their application helps clarify why this choice is correct.