Cross-method assessment of coliphage detection methods in the framework of EPA regulatory standards.

This article evaluates the performance and practicality of US EPA-approved coliphage enumeration methods, specifically US EPA Method 1642, in comparison to fecal indicator bacteria (FIB) and molecular microbial source tracking (MST) techniques for monitoring recreational waters impacted by non-point source pollution. Conducted over a year in a North Carolina estuary, the study found low concentrations of male-specific (MSC) and somatic coliphages (SC) with poor correlation to traditional FIB and MST markers, and noted that Method 1642 is labor-intensive and time-consuming, potentially limiting its routine applicability. The feasibility assessment revealed that culture-based FIB methods combined with rapid molecular tools like qPCR offer a more cost-effective and timely approach for water quality monitoring in systems without direct wastewater discharge. The findings provide guidance for selecting appropriate microbial indicators and methods for recreational water quality assessment, emphasizing the need for further research on coliphage utility in environments dominated by diffuse fecal contamination.