Calls to cull beavers are getting stronger because the growing number population is causing millions of euros in damage to dykes, rail and other infrastructure, RTL Nieuws has found.

Repairs to dykes and other water defences cost over €2 million last year while Dutch track manager ProRail said it clocked up “from €1 million to €10 million” in damage to rail infrastructure every year.

The beaver (Castor fiber) was reintroduced in the Netherlands in 1988 and since then the number of “nature’s engineers” has increased to over 5,000 across much of the Netherlands.

The beavers’ activities are beneficial to nature, supporters say, and promote biodiversity.

But the water boards said the steady growth of the beaver population is worrying, with the repair bill for dykes, expert help to move or chase away the beavers coming to over €5 million over the last four years.

Despite its protected species, beavers are already being culled in the province of Limburg and, the Hunze and Aa’s water board, which manages water defenses in Groningen and Drenthe, said it may have to follow suit.

“It is increasingly difficult to move beavers to sites where they can do no harm. The time is getting near when we will have to kill the captured animals,” a water board official said.

The problem is manageable in summer, Dolf Moerkens of waterboard umbrella organisation Unie van Waterschappen said because then there is time to find an alternative site. But when damage is discovered between October to March, when water levels are high, repairs will have to take place immediately, and than means the beavers have to be removed immediately.

The organisation is calling for a “straightforward protocol” to tackle the beaver and is in talks with the experts about how to proceed. The primary goal is to prevent culling by making sure places where beaver activity would be dangerous cannot be accessed by the animals.

Beavers are not the only animals undermining infrastructure. Earlier this year badgers tunneling under the tracks stopped train services in several places.