Children are putting themselves in danger at a reservoir building site.

Now Yorkshire Water and Kirklees Rural Police have urged parents to warn their children to keep away from the £5m project to replace the spillway at Butterley Reservoir in Marsden.

Project manager Lee Laherty said: “Since starting the project we have become concerned about the safety of local children, some of which have been seen entering the construction boundary.

VIDEO: Butterley Reservoir before the work began

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“Our contract partner, Mott MacDonald Bentley have witnessed children gaining unauthorised access to the site and on two occasions boys have been seen jumping over the wall on the access road, which is currently closed to the public.

“A group of children were also caught sledging down the reservoir embankment, and one of the group came into the working area and climbed onto a 13 tonne excavating machine.

“I appreciate that to children our sites, along with the large machinery might seem exciting. However, they are very dangerous and we need to try and keep them safe and away from danger.”

READ MORE: More work continues to renovate Butterley reservoir spillway

READ MORE: Safety fears for children as Yorkshire Water start work at Butterley

In a plea to parents he added: “We have put up additional safety signs at the reservoir, targeted at children, around the perimeter. However, we’d be very grateful if you can help us reinforce our safety message by explaining to your child why they should not enter our construction site, along with the associated dangers.”

The scene at Butterley Reservoir's spillway, where Yorkshire Water contractors Mott MacDonald Bentley (MMB), have started work to replace the historic structure due to safety concerns

Following reports of children entering the construction site in March, Yorkshire Water had sent education guides to Marsden Junior and Infant School to warn the children about the dangers of entering the site

The project is due for completion in summer 2017.

The stone spillway was designed by Thomas Hawksley in 1906.

An inspection of the site by an independent Panel Engineer highlighted the need to adapt the spillway to ensure it continued to meet with legislation, in particular, the Reservoirs Act 1975.

Original plans to replace the spillway were fought by many local residents and conservationists.

They feared the historic stone would be replaced with concrete.

Yorkshire Water amended the plans and they have now been approved.