What is a primary goal of implementing buffer rules in watersheds?

A primary goal of implementing buffer rules in watersheds is to ensure sustainable water quality. Buffer zones, which are areas of vegetation established along waterways, serve as a protective barrier. They help filter pollutants from runoff before they enter water bodies, thereby reducing contamination and supporting the health of aquatic ecosystems. By maintaining these buffer zones, it is possible to enhance water quality by minimizing sedimentation, nutrient loading, and other harmful substances that might otherwise degrade the water environment. This helps sustain healthy water systems crucial for both ecological balance and human use.

The other choices do not align as closely with the core purpose of buffer rules. For instance, promoting agricultural expansion could lead to increased runoff and decreased water quality, while limiting residential development or improving urban infrastructure doesn't directly address the ecological function of watersheds that buffer zones are designed to protect.