Is Bristol behind Gloucester Docks' silt crisis?

A city's docks' silt levels have become so high over the summer months that multiple boats have become trapped as their drivers have attempted to sail through.

There have been growing suspicions among locals that the crisis has partially been caused by water being pumped out of Gloucester's canal to supply drinking water to people in Bristol.

But leaders at the Canal & Rivers Trust (CRT), which manages the Gloucester and Sharpness Canal, said the reason for this year's unusually high levels is complex, caused by multiple factors.

A spokesperson for the charity said the second phase of its £4m dredging programme will begin later this month.

This is little help to holidaymakers who say the experience is putting them off returning to the city with their boats.

Richard Jones told the BBC earlier this week: "It's so dangerous. The water level here should be at least 15ft (4.5 metres) deep and at the moment it is 2ft (0.6 metres) deep."

Silt typically appears in Gloucester Docks as water has to be pumped into the canal from the River Severn to keep the canal functioning.

During long periods of dry weather river levels are lower, and as water is pumped in from the river, so is more silt.

High tides can also cause more issues as it can push more silt upstream.

"This has been really compounded by a technical issue with our water management software," said Ben Cottam, CRT's regional director for Wales and the South West.

"That's meant a lower water level in the dock than we would normally have."

Sensors can measure water levels in docks so people know when to pump more water in or out of the basin.

"Silt levels in the docks are already high with the software error revealing the issue.

"We're very sorry that this has caused the concern it has caused," Cottam added.

Bristol Water pay to take water from the canal which they clean and then deliver to the taps of about half of Bristol's residents.

The water company has been doing this since the 1960s, but following multiple years of long dry summers, silt is having more of an impact.

It is not clear how much money Bristol Water pays CRT but the trust said it helps maintain the canal.

It has led to some concerns that if Bristol Water did not pump water out of the canal then CRT would not have to pump in so much water and silt from the river.

Alex McIntyre, Gloucester's MP, wants the utility to do more to reduce the build up of silt.

"People in Bristol need their drinking water, but people in Gloucester need to be fairly compensated for the impact that has here," he said.

"I want to see them investing in a filtration system that will stop this problem in the first place and will be pushing hard to make this happen."

The water company and the CRT have been working together to try and reduce the amount of silt coming into the canal by coordinating pumping water in and out.

"We're looking at what they need, when do they need to pump and when do we need to pump and we are seeing some real benefits in matching those schedules," Cottam said.

It is hoped this work, which began earlier in the year will minimise the amount of silt in the dock over the coming months.

A spokesperson for Bristol Water said the responsibility of silt management is with the CRT but they "are working with the trust to improve operations to try and reduce sediment transfer".

"During dry weather river inflows into the canal reduce, meaning that the volume pumped into the canal from the Severn increases to support both shipping and public water supply."

Trust leaders said they plans to resume dredging in a few weeks' time.

The charity is investing £2m in the dredging, a quarter of its overall budget - spending £4m in the last two years.

A trust spokesperson said in the first phase of dredging, more than 37,000 tonnes of silt was removed, calling it "by far the biggest dredging operation anywhere on our nation-wide canal network".

It will use a backhoe dredger to lift the silt out of the basin and put it on a barge.

The barge will then head downstream to a site near Parkend where the silt will be deposited on agricultural land.

CRT spend a quarter of their budget on dredging Gloucester docks and the surrounding canal.

It has a huge network of waterways across England and Wales and some feel spending this much on such a small stretch is not viable.

McIntyre wants a better pumping system but others think they need to find a new source of water to be put into the canal.

Tony Conder, from Gloucester Heritage Harbour, thinks getting the sewage treatment works such as Netheridge to deposit clean water in the canal could solve the silt issue.

"Seven Trent have a long-term plan which would see the water that comes out of the Netheridge sewage works possibly [going] back into the water system," he said.

Conder added that the dredging is a temporary solution, which will keep happening as drought impacts river levels.

"The £2m that they spent scrapes the four or six feet off the top of the surface of the mud and leaves 14 feet or whatever it is of mud still in the dock."

Conder believes different organisations, from the CRT and water companies, to the city council and the Environment Agency should be looking for a long term solution.

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