Monitoring Urban Waterways with AcquaDecode — A Pilot in the Greater Geneva Area

Urban waterways are among the least studied aquatic environments in Europe. Channelled, managed, and often directly affected by stormwater and wastewater inputs, they are frequently assumed to support low biodiversity. Systematic monitoring is rarely conducted — partly because traditional survey methods are resource-intensive, and partly because the results are expected to be unremarkable.

This pilot programme, conducted in partnership with a cantonal environmental agency, deployed AcquaDecode across three urban waterways in the Greater Geneva area over a two-month period, to test both the feasibility of eDNA monitoring in urban settings and the ecological value of the data produced.

The sites and sampling design

Three sites were selected to represent a gradient of urban influence: a largely natural tributary on the urban fringe, a partially channelled stream crossing a mixed residential and light industrial zone, and a heavily managed urban drainage channel in the city centre.

At each site, three water samples were collected monthly at fixed stations, and processed on-site using AcquaDecode within three hours of collection.

Results: more than expected

The survey detected 18 species of fish, amphibians and macroinvertebrates across the three sites — significantly more than expected based on visual observations and historical records. At the most natural site, AcquaDecode detected a signal consistent with the presence of European eel (Anguilla anguilla), a species listed as Critically Endangered on the IUCN Red List, and not previously recorded at that location.

At the urban drainage channel — the most impacted site — eDNA signals revealed the presence of three species of non-native ornamental fish, consistent with aquarium release, including one species not previously recorded in Swiss freshwaters. The agency immediately escalated the finding to the national invasive species authority.

Urban eDNA monitoring: what this pilot demonstrated

The results of this pilot suggest that urban waterways may support greater biodiversity than commonly assumed — and that eDNA monitoring is sensitive enough to detect it, even in water with elevated turbidity and organic load.

For environmental agencies managing urban water bodies, AcquaDecode offers a practical tool for baseline monitoring, compliance assessment, and early detection of invasive species — without the logistical demands of traditional survey methods.

Key figures

• 3 sites · 2 months · 18 species detected
• 1 Critically Endangered species confirmed (European eel)
• 1 non-native ornamental species — first record in Swiss freshwaters
• 3-hour on-site turnaround per sampling session

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