KEY POINTS:
Spectators gathered and campers moved to higher ground as hundreds of cubic metres of water spilled from the Waitaki Valley in North Otago yesterday.
The water was released through the Benmore Dam in an attempt to flush out didymo in the Waitaki River.
Environment Canterbury had to warn campers and boaties that the river would swell quickly, tripling its size.
In the 24-hour controlled flooding, water from the dam spilled over at 950 cubic metres a second, more than four times its usual flow.
