Where do buffers apply specifically in the Catawba watershed?

The correct choice reflects the areas where buffers are most effective and relevant within the Catawba watershed. Buffers are typically established along mainstem rivers and lakes because these bodies of water are significant in terms of both hydrology and environmental health. They play a crucial role in improving water quality by filtering pollutants, reducing runoff, and providing habitat for wildlife.

In contrast, while buffers may be beneficial in other areas such as tributaries or private properties, the choice specifies that the focus is on mainstem rivers and lakes. This distinction is essential because the scale and impact of buffers are particularly pronounced in these key water bodies that serve as primary channels for flow and ecological connectivity in the watershed. Thus, the correct answer appropriately identifies the primary areas where buffers have the greatest impact in this specific context.