Surface water sample (10 L) concentrated by dead-end hollow fibre ultrafiltration (R180 Inuvai), followed by secondary concentration using Amicon Plus-15 centrifugal ultrafiltration units (10 kDa cutoff). Total DNA/RNA extracted from 140 L of concentrate using the QIAamp Viral RNA Mini Kit (Qiagen). Libraries prepared with the Twist Total Nucleic Acids Library Preparation EF Kit 2.0 and enriched using the Twist Comprehensive Viral Research Panel by solution hybridization capture. Paired-end sequencing performed on an Illumina MiSeq.