Will £4m dredging solve a dock's silt problem?

The £4m dredging project to remove silt from a city's docks has begun, but what is the long-term solution to prevent it from returning?

Silt levels at Gloucester Docks became so high this summer that water depths fell below navigable levels, leaving boats trapped and forcing the docks to close.

The Canal & River Trust (CRT), which manages the Gloucester and Sharpness Canal, began dredging on Monday, with the work costing the trust about half of its total dredging budget.

But Gloucester MP Alex McIntyre said this was only a short-term solution, adding: "We are going to keep seeing this problem as climate change gets worse."

Silt typically enters Gloucester Docks because water has to be pumped from the River Severn into the canal to keep it functioning.

During long periods of dry weather, lower river levels can mean water is drawn from areas closer to the riverbed, where the concentration of sediment is often higher. This can result in more silt entering the system.

There has also been speculation that the build-up of silt has been made worse due to water being pumped from the Gloucester and Sharpness Canal to supply drinking water to people in Bristol.

There has been a long-term agreement since the 1960s to supply water to Bristol from the canal.

This has led to some to question if Bristol Water stopped this process, would CRT not need to pump as much water, and therefore silt, from the River Severn?

Tony Conder, from Gloucester Heritage Harbour, said the problem was most of the pumping takes place during August and September.

"In August the river is running very low, and in September it is full of sand and silt stirred up by the tide, which rushes past Gloucester and leaves it in the river," he said.

McIntyre said he had got "nothing against Bristol residents getting their water but it can't come at the cost of what is a historic dock here in Gloucester".

A spokesperson for Bristol Water said responsibility for managing silt lies with the CRT, but added that it was "working with the trust to improve operations and reduce sediment transfer".

CRT says the dredging will increase navigation depths and support boaters and waterside businesses.

The trust said river levels were so low that the dredger would have to clear its own channel before Llanthony Swing Bridge before it could begin dredging the docks basin itself.

It is difficult to know how long the dredging will take, but it is likely to continue into the winter, said a spokesperson.

It is also unclear when tall ships will be able to re-enter the docks, as the trust's main aim is to reopen them to regular boat traffic first.

As dredging continues, CRT says it will gain a better understanding of what further work is needed to allow larger vessels back in.

Ben Cottam from the trust said: "We know people are frustrated by the impact that siltation has had in Gloucester. Boaters, businesses, residents rightly cherish the Docks and want them to be well maintained and that's why we are doubling our investment to address the problem.

"We want local communities and businesses to know that we remain committed to doing all we can."

McIntyre said he did not believe dredging to be the solution to this problem. He said there should be an investment in "proper filtration".

"We're going to keep seeing this problem as climate change gets worse, we have drier summers and more droughts," he said.

"The answer has to be to stop the silt coming in the first place."

The CRT will also look at other measures that could be taken to reduce the amount of silt entering from the River Severn and improve the long-term resilience of the Docks.

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