Which of the following is a method for reducing nutrient inflows to water sources?

Avoiding livestock access to water is an effective method for reducing nutrient inflows to water sources. Livestock can contribute significant amounts of nutrients, particularly nitrogen and phosphorus, through their waste. When animals have unrestricted access to water bodies, they tend to defecate near or in the water, which leads to nutrient pollution. This can result in harmful algal blooms and other negative ecological impacts.

By keeping livestock away from water sources, you minimize the direct input of these nutrients into the water. Additionally, this practice can help protect the banks from erosion and sedimentation, which is also beneficial for maintaining water quality. This method can contribute to healthier ecosystems and better water quality for both human use and wildlife.

In contrast, the other options would likely lead to increased nutrient inflows, making them less effective for the goal of protecting water bodies. For example, encouraging unrestricted runoff can lead to the runoff of fertilizers and sediments from urban areas into bodies of water, while using fertilizers directly in water bodies introduces additional nutrients. Similarly, promoting urban development near water sources can increase pollution from human activity and runoff.