Which measure most directly reduces nutrient pollution entering waterways?

• A. Upgrade wastewater treatment with tertiary nutrient removal
• B. Expand transit and EVs
• C. Deploy green infrastructure
• D. Promote conservation

Answer: (A)

Directly cutting nutrient pollution into waterways comes from removing nutrients before they enter the water. Upgrading wastewater treatment to tertiary nutrient removal adds steps specifically designed to remove nitrogen and phosphorus from the effluent. This means the water that is discharged from treatment plants contains far lower nutrient levels, addressing a major and identifiable source of pollution right at the source.

Phosphorus and nitrogen in treated wastewater are common culprits behind eutrophication, which fuels algal blooms and depletes oxygen in aquatic systems. Tertiary removal uses processes like advanced biological nutrient removal, chemical precipitation, and filtration or membranes to target these nutrients, making the discharge much cleaner for downstream ecosystems.

Other measures can help, but they don’t target the pollution source as directly. Expanding transit and electric vehicles mainly reduce air emissions and fossil fuel use, not nutrient discharges. Green infrastructure helps manage runoff and can lower nutrient loads from urban areas, but its effectiveness depends on design, maintenance, and local conditions. Conservation can reduce overall resource use, including irrigation and fertilizer, yet its impact on nutrient loading varies and isn’t a guaranteed point-source treatment.