Founder’s Briefs: An occasional series where Mongabay founder Rhett Ayers Butler shares analysis, perspectives and story summaries.

From a hillside overlooking Lake Toba, the vast volcanic basin at the heart of Sumatra, Wilmar Eliaser Simandjorang looks down on what he calls both a blessing and a warning, reports contributor Sri Wahyuni for Mongabay.

Once the first district leader of Samosir, Wilmar has spent his retirement rewilding parts of this landscape sacred to the Batak people. “If we don’t pay attention to this, Lake Toba will be just a memory,” he says.

That memory is fading fast. Pollution, logging and unchecked plantations have clouded the waters of what was once among Indonesia’s purest lakes.

“The forest is being cut down, both legally and illegally — biodiversity is being burned,” Wilmar says. “Rainwater is just running off; it carries ash, trash and pesticides into the lake.” Research published in 2024 confirmed nitrogen levels above national safety thresholds, threatening fish and water quality.

The deterioration stings for those who remember when people would ask travelers to bring back a flask of Toba’s crystal water.

“Now? Just cooking rice with it will smell,” Wilmar says. He has watched the district lose nearly a quarter of its old-growth forest since 2002. Yet he persists, planting trees, urging families to blend fruit and forest crops, and teaching children to see trees, birds and soil as kin. “I believe forests will be sustainable if people feel they are part of their lives,” he adds.

His modest crusade has taken place as larger institutions stir. This year, the Batak Protestant Christian Church, Indonesia’s biggest, called for the closure of PT Toba Pulp Lestari, the dominant plantation company in the area blamed for decades of conflict and ecological damage. “The most painful fact is that the presence of PT TPL has triggered various social and ecological crises,” declared the Reverend Victor Tinambunan. The firm denies wrongdoing.

This year, fires have scorched 16 hectares (40 acres) of land Wilmar spent years regreening.

“The land I turned green, which was just starting to show results, went up just like that,” he says. Yet he continues to plant and to preach renewal, even after threats from illegal loggers and indifference from officials. His faith, rooted in duty rather than reward, remains unshaken.

“We can turn this destruction into hope,” Wilmar says. “But it takes will, knowledge, and love.”

Read the full story by Sri Wahyuni here.

Banner image: Wilmar Simandjorang on his conservation land that burned in 2025. Image courtesy of Wilmar Simandjorang.