Nice

Nice built its own river gauges because the state only forecasts the big rivers, and the network is unusually honest about how far a reading travels. Instrumentation started in 1983 on the Paillons, when a tunnel was dug into the river bed: nine rain gauges, ten water-level stations and four doubt-clearing cameras now feed a flood alert device whose job is to evacuate and close that tunnel before water reaches the surface. The Magnan was equipped from 2013 with its own gauges and cameras used for image processing, inside a forecasting project the operator still describes as experimental; on the Cagne and Malvan, monitored since 2019, the local alert system is in the métropole's own words still being defined. Across the three basins the métropole owns fourteen rain gauges, twenty level stations and seven cameras on a round-the-clock engineering rota. One threshold closes a tunnel; the others produce a bulletin, and no published evaluation says how often any of it has fired.

The camera estate went the other way — very large, and evaluated by nobody who runs it. The network began in 2001 with fifty cameras and the city now reports more than 4,775 in service: one in front of every school entrance, over a thousand on the tramway, body cameras on every patrol, a forest-fire detection camera on a hillside since 2023. Ninety agents work the urban supervision centre around the clock across three rooms, footage is kept ten days, and the centre answers roughly 2,000 judicial requisitions a year while also driving 1,872 alert boxes, 316 emergency call points, 210 loudspeakers and the retractable bollards on the seafront. France's national audit court, reviewing 58 communes across 2014 to 2018, found Nice's the largest estate in its sample and reported no overall correlation between the existence of video-protection systems and either the level of crime in public places or clearance rates — and noted that its own 2011 recommendation to evaluate the results was still unmet a decade later.

Then the algorithms arrived, and the courts drew the line. During the 2019 carnival the city ran a facial-recognition test at one entrance, matching passers-by against fictional watchlists; the city reported success, and the national data-protection authority asked for objective measurement of error rates, image-quality conditions and bias risks, which the city said it lacked the perspective to supply. The system that actually ran was duller and lasted longer: from 2020 an algorithm analysed the cameras filming 144 school entrances and raised an alert whenever a vehicle stayed parked more than five minutes. After an inspection in 2023 and a formal notice in 2024, the authority held in May 2025 that the treatment was not authorised, and on 30 January 2026 the Conseil d'État rejected the city's appeal — holding that the law permitting video surveillance of public roads cannot, in its silence, be read as authorising algorithmic treatments that systematically and automatically analyse the images collected. That ruling applies to every French municipality. The city's open-data portal sits quietly beside all of this: 268 datasets, every one under the national open licence, and none created since June 2023.