This study evaluates these two newly developed USEPA coliphage methods, which are under consideration for approval as required by the Groundwater Rule (GWR). Method 1601 is a qualitative two-step presence-absence procedure and Method 1602 is a quantitative single agar layer (SAL) procedure. This evaluation reports on their assessment of these methods for testing the vulnerability of groundwater for viral/fecal contamination as used for routine monitoring.