How can excess fertilizer application harm nearby waterways?

Excess fertilizer application harms nearby waterways by accelerating cultural eutrophication, a process where nutrient runoff—specifically nitrogen and phosphorus—enters aquatic ecosystems.1

When these nutrients reach lakes, rivers, or coastal waters, they trigger rapid growth of algae and other microscopic organisms, forming water blooms. These blooms negatively impact the environment in several ways:21

• Oxygen Depletion: As the excessive plant matter dies and decomposes, the process consumes vast amounts of dissolved oxygen, leading to hypoxia—a state of extremely low oxygen that can cause massive fish kills.21
• Light Blockage: Dense surface blooms prevent sunlight from penetrating the water, which inhibits the growth of necessary underwater vegetation.1
• Toxicity: Certain blooms can produce toxins that poison local wildlife.1
• Dead Zones: In severe cases, these conditions create "dead zones" where oxygen levels are too low to support most forms of aquatic life, devastating local food chains and economies.21

Improving agricultural practices is essential to curbing this degradation and protecting vital water resources.1