One of Wales's historic canals is on the brink of drying up amid an "urgent" water shortage. The operators of the Monmouthshire and Brecon Canal say the 225-year-old watercourse will start to go dry without imminent rainfall.

The Canal & River Trust has called for support to secure the future of the canal, which draws its water from the nearby River Usk. Legal changes mean there are strict limits on the water that can be diverted from the river, prompting the Trust to warn a drop in water levels would be "disastrous" for fish, invertebrates, mammals and birds and threaten jobs which depend on the canal.

The canal winds its way through the Bannau Brycheiniog National Park, which was known as the Brecon Beacons National Park, and the Blaenavon industrial landscape World Heritage Site.

Mark Evans, the Trust's regional director, said: "Since the canal was built at the end of the 18th Century, it has drawn most of its water from the River Usk. However, the application of 21st Century changes in legislation means that supply of water is now severely limited.

"The prioritisation of the River Usk, without an alternative supply of water in place, has serious consequences for the integrity of the canal, impacting boaters, jobs and wildlife along this ecologically-rich waterway."

He added that this now poses a serious long-term risk to the future of the Monmouthshire and Brecon Canal and the Trust is faced with the unwanted choice between severely restricting its usage or having to pay high costs for an alternative source of water.

The Trust has said it is in talks with Welsh Water about possible alternatives but there is "no solution in sight" which the charity can afford.

Cardiff has said any arrangement between the Trust and Welsh Water would be a commercial decision so it shouldn't play a part, according to the BBC.

Tracey Leake-Jones, who runs the Bridge 46 to Five Locks canal group, told the broadcaster: "Everything the canal supports is at threat - we risk losing the jewel in the crown of south Wales."

She urged the Welsh government to step in to bring all the main players together to thrash out a solution to safeguard the canal's future.

Gail Davies-Walsh, chief executive of Afonydd Cymru, which represents river groups across Wales, said the canal took about 30% of the Usk's total flow in 2022 and limits are needed to make sure species and habitats can survive during dry summers and periods of low flow.

A Welsh Water spokesman said the Usk is a primary source of drinking water for about 250,000 customers across south east Wales but it remains one of the least drought resilient supply areas, with limited water resources to deal with the impacts of climate change and population growth.

He added: "We have proposed in the driest of years to supply some customers with water from the River Tawe through an emergency pumping station and use this spare capacity in abstraction from the River Usk to support the canal."

This would come with a cost and discussions are ongoing over whether the option would be affordable for the Trust. The spokesman said: "To provide this free of charge or risk the future supply of drinking water to our customers, isn't an option for us."

The Welsh government said protecting and enhancing Wales's environment and natural resources is key to addressing the climate and nature emergencies.

A spokesperson said: "The limits placed on the licences were in line with the amounts applied for by the Canal & River Trust."

They added any deal between the canal and Welsh Water would be a commercial contractual decision in which the Welsh government shouldn't play a role.