Near-Source Wastewater Surveillance of SARS-CoV-2, Influenza A, and Respiratory Syncytial Virus With Spatiotemporal Evaluation of Pepper Mild Mottle Virus as a Fecal Indicator.

Wastewater-based epidemiology (WBE) is increasingly transitioning from treatment plant scale monitoring toward community-scale surveillance to provide higher spatial resolution. However, the influence of monitoring scale on signal stability and normalization performance remains insufficiently characterized. This study evaluated the dynamics of SARS-CoV-2, influenza A (IAV), and Respiratory Syncytial Virus (RSV) at five near-source pumping stations between October 2022 and September 2024. The monitoring sites were selected using the Social Vulnerability Index to ensure representative coverage, and the catchment populations were estimated by integrating census data with physical sewershed boundaries. Wastewater viral concentrations exhibited strong associations with clinical hospitalizations, with maximum Pearson correlations occurring at lead times of 1 day for RSV and 8 days for SARS-CoV-2. The performance of Pepper Mild Mottle Virus (PMMoV) as a fecal indicator was target-specific and scale-dependent. PMMoV normalization improved predictive correlations and extended the lead time for IAV to 7 days but reduced correlation strength for SARS-CoV-2 and RSV, suggesting that raw viral loads may better reflect community shedding for certain pathogens at the neighborhood scale. Comparison with downstream wastewater treatment plant influent revealed substantial signal smoothing at larger spatial scales, whereas upstream pumping stations exhibited higher hydraulic volatility. Small catchments serving fewer than 600 residents showed large signal instability and frequent stagnation. Significant PMMoV seasonality was observed, with consistent winter and spring peaks across sites. Together, these findings indicate that near-source WBE offers reliable neighborhood-level surveillance and that the effectiveness of normalization depends on both the viral target and catchment characteristics.