The east London borough of Newham boasts the largest tidal mill in the world. The Three Mills’ buildings, which were in operation for almost 800 years, are grade one listed and the area is protected by the council as a dedicated conservation site due to its “special architectural and historic interest”. And earlier this year, in this unique area lived a dockless rent-a-bike, crudely poking out of the mud.

I have previously written about the plight of searching for these such bikes in London, only to locate them at the bottom of a river or canal. In Manchester, Mobike, one of the major rent-a-bike companies, has had to ramp up its prices due to the number of bikes being vandalised or ending up in the city’s canals.

Which got me thinking: who is actually was responsible for the bikes once they end up in their watery docking stations. Whose responsibility was it to get the bike out of this east London conservation area?

In China, where the bike-sharing boom began, mountains of abandoned rent-a-bikes are now a regular feature of many cities. But in the UK, they aren’t just left wherever they’re dumped. Walking along an east London canal, I found numerous shopping trolleys, general rubbish, and a weirdly high number of motorbikes, yet there weren’t that many rented bikes. In fact I found only one other – a Boris Bike. Considering a friend of mine reported seeing several bikes in that same stretch of water only weeks before, I knew someone was getting rid of them.

The Canal and River Trust (CRT), the charity that manages the canals, told me that it has an arrangement with Transport for London (TfL) with regards to removing Boris Bikes. CRT fishes the bikes out and then bills TfL for the trouble.

Although this particular relationship has been established, no similar scheme has yet been agreed with the dockless bike companies. The London CRT estimates that it has pulled 30 of the bikes from canals – bear in mind they were only introduced to the city last year – and is now asking people not to dock them nearby. Yet the CRT is still in “negotiation” with the firms about how much the removal will cost.

Mobike told me a different story. According to a spokesperson, it “has robust operational response teams who move mis-parked bikes on a very short turnaround.” So it’s the company who should be dealing with them, not CRT – an already overstretched charity.

The spokesperson also said that the GPS trackers in the bikes “allow us to know where all our bikes are, at all times.” Yet the Three Mills bike was there for almost a month, hardly a “very short turnaround”. It’s hard to imagine the GPS would have lasted long in the tidal waters of the Lea River, which brought into question whether the company even knew it was there.

Dockless rent-a-bikes bring much to the city. They have opened up cycling to a greater number of people without significantly reducing the use of Boris Bikes. Despite this, the companies must remain responsible for the bikes otherwise they could end up becoming a blight to cities and especially waterways, where they are particularly difficult to reclaim.

I’ve told Mobike about their bike at Three Mills, lets see how ‘robust’ their reclamation teams really are.