The old dam came down — and the fish came back

The day they took the old dam out, the oldest fisherman in the village went down to the river in a boat to have a look. When he came back he said four words: "The fish are saved."

The dam on the Qinglong River was built in the 1970s. For years it watered tens of thousands of mu of good farmland, and the village was proud of it. But half a century passed. The irrigation system was rebuilt and upgraded, and the dam became an ornament — and then a culprit. It cut the river in two, and with it cut the road the fish used to come home.

The most famous fish in the Qinglong is the ayu, a sweetfish. It hatches in fresh water, drifts down to the sea to grow, then swims back upstream to spawn. Block the river and you block the road. The ayu vanished from the Qinglong for decades. The old fishermen could only tell their grandchildren the legend of the years when the fish were so thick they jumped into the boats.

The proposal to demolish the dam came out of an ecological survey. The report said the river's water quality had met standards after years of cleanup, and that ayu fry were appearing downstream every year — arriving at the foot of the dam, hitting the wall, jumping, failing, and coming back the next season. "The fry have been waiting below that dam for more than ten years," the survey said. "They are waiting for one way up."

The review meetings ran three rounds and got loud. The objections were practical: the dam had fed an irrigation economy; was it not a shame to lose it? A water engineer's answer turned the room. "This dam has finished its historic mission. Its usefulness is zero, and its ecological cost rises every day. It is time for it to take its bow." The decision: take the dam down, and build a modern stepped-water landscape on the site, half of it a fish ladder.

Demolition day was a ceremony. The excavator bit a notch into the concrete, the river poured through, and the crowd cheered. But the real climax came three months later, when the migration season arrived.

The old fishermen kept watch below the site. First a few ayu nosed through the gap. Then they came in numbers, driving upstream through the stretch the dam had blocked for fifty years, throwing spray. An underwater camera at the monitoring station caught it, and the footage became a nature documentary: fish passing the stubs of the old dam, heading up to the gravel beds where their grandparents had spawned. A road closed for decades was open.

Restoration has a particular beauty to it: you remove something man-made, and nature hands back something natural. It may be the highest-yield subtraction in the world.

The next year the station found newly hatched ayu fry upstream — the first in decades. The fishing village revived its annual Ayu Festival. The point of the festival is not eating; the catch is tightly limited. It is watching. In migration season the platform above the old dam becomes a nature classroom for children. The engineer who argued for demolition was invited to teach a class. He went through the technical details, then said: "I have built dams and I have taken dams down. Building was right. Taking it down was right. The times changed, and the standard of right changed with what people understand about nature."

Today the ayu population recovers year by year, and "the ayu came back" has become the calling card of the region's ecological work. The stub of the old dam on the bank was not cleared away. It was kept as a ruin. Grass has come up in the seams of the stone. Children climb on it. A plaque gives it two identities:

"It irrigated ten thousand mu of good farmland. It also cut a river in half for fifty years. Now its credit and its debt both go back to the river."