Dutch Beavers Are Tunnelling Into Dikes, and Water Boards Now Track Them

Updated on October 2, 2026

Beavers reintroduced in 1988 dig into Dutch dikes, and in 2026 water boards are radio-tagging them to find burrows hidden underwater.

Beavers vanished from the Netherlands in the early 19th century and were reintroduced in 1988. Their comeback has a catch for a country where a quarter of the land lies below sea level. A Guardian opinion column from 28 August 2025, summarized by Slashdot, put the population above 7,000 and warned about burrows under roads, railways and, worse, inside dikes.

Counts differ: Green Matters gives 6,000 to 7,000. Note too that the source is a column, not a news report.

Entrances below the waterline are the heart of the problem: dike managers often cannot see the tunnels.

The detail that matters is visibility. Jelmer Krom of the Rivierenland water board describes tunnels reaching 17 metres into a dike, and the entrances are usually underwater. A dike specialist quoted by Green Matters, Frans van den Berg, says beavers dig below the waterline, so managers often cannot see what is going on inside. Night patrols with thermal cameras during high water give mixed results.

This is not new. In November 2023, NL Times reported burrows in the Waaldijk and Maasdijk, found only during an extra inspection beyond the standard pre-season check. The holes were sealed with stones. Shooting is a last resort in Gelderland and prohibited in Noord-Brabant, since beavers are protected. Moving them does little, because they tend to come back.

What happened next is the interesting part. In early April 2026, the Aa en Maas water board announced its first tagged beaver along the Maas in Brabant. It is a joint project with the Zoogdiervereniging, three other water boards and Van Hall Larenstein, and a water board in Drents Overijsselse Delta had already tagged animals the year before. The transmitter is fixed to the tail, much like a livestock ear tag, and can locate animals even inside burrows. Tagging pauses from 15 April to 1 September for the breeding season.

By 18 May 2026, the board's beaver expert Ronald Wolters was out on the Maas near Macharen with an antenna, tracking tagged animals. The board calls it a new asset for protecting dikes. The stated goal is to understand behaviour at high water and act early, while letting beavers move freely.

Our take: this is the sensible shift from guessing to measuring. Still, finding a hidden tunnel before the river rises beats discovering it when it collapses.

Opinion · If I were…

If I were the Rivierenland water board, I would treat the tagging study as a way to cut blind inspection work, not as a cure. Burrow entrances sit underwater, so the first job is knowing where the animals actually spend high-water nights.

I would also keep the cheap, boring fixes running in parallel: sealing holes, mesh, stones, clearing willow. The sources show no new dike breach and no fresh count. Evidence first, then budget.

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Original source: Slashdot (summarizing The Guardian)

Produced with AI support and reviewed by the newsroom

Falcon · Signals analyst · Riyadh

“A transmitter on a tail will not stop a tunnel, but it might tell you where to look before the river rises.”