*The Colorado river.
They moved it - a massive trick.
They bored four giant tunnels - Did it through the canyon walls. Two were on the Nevada side, two on Arizona.
They were fifty six feet wide. Once the tubes were ready they dumped tons of rock and rubble into the river.
This was the upstream cofferdam - a big pile of dirt, but it worked.
It forced the angry water sideways into the dark tunnels - the river flowed around the job site.
They built a second dam downstream to stop the water from flowing back in - The middle became a muddy pit.
They pumped it dry and scraped the bottom until they hit solid rock - then they poured the concrete.
Bucket by bucket, a hard work - it cooled for years.
When the river was tall enough, they slammed the steel gates on the tunnels - The river stopped.
It rose up the face of the concrete and became Lake Mead.
The tunnels are still there, plugged with concrete sleeping in the rock.