How can a groundwater source be screened for surface water intrusion and what treatments might be applied if intrusion is detected?

• A. Monitor turbidity, nitrate, temperature, and microbial indicators; if intrusion detected, apply coagulation, filtration, and disinfection optimization, or blend with clean source.
• B. Monitor only pH and chlorine residual; no additional treatment is necessary.
• C. Only rely on source aging data; no monitoring required.
• D. If intrusion detected, switch to bottled water.

Answer: (A)