Gnawing through tree trunks and bureaucratic red tape alike, a colony of Czech beavers recently built a dam exactly where local administrators needed it.

Conservationists often talk about species or landscapes performing “ecosystem services” that benefit human civilization. These beavers in the Brdy Protected Landscape demonstrated this phenomenon to a stunning degree, saving the local government 30 million Czech crowns—around $1.2 million.

Management staff in Brdy were looking for planning permission for a dam and reservoir project from the Vltava River Basin authorities, but the process was lagging. That’s when local beavers built their dam in the proposed location virtually overnight. When the staff woke up, their problems were seemingly solved.

“They could not have chosen their location better,” according to Daniela Lazarová at Radio Prague International, “erecting the dams on a bypass gully that was built by soldiers in the former military base years ago, so as to drain the area.”

Beavers are said to be second only to humans in their ability to transform the ecosystems in which they live, and the colony is believed to consist of just 8 animals. Despite their numbers, they are remarkable engineers.

“The Military Forest Management and the Vltava River Basin were negotiating with each other to set up the project and address issues regarding ownership of land,” Bohumil Fišer, head of the Brdy Protected Landscape Area Administration, told Radio Prague.

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“The beavers beat them to it, saving us CZK 30 million. They built the dams without any project documentation and for free.”

Ecologists inspecting the dams said they will last a long time and do the job of draining the area well, while offering good conditions for the rare stone crayfish, frogs, and other species that thrive on wetlands.

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“Beavers always know best. The places where they build dams are always chosen just right—better than when we design it on paper,” said Jaroslav Obermajer, head of the Central Bohemian office of the Czech Nature and Landscape Protection Agency (AOPK).