They managed to lower the water level by 10-feet and recover 40-pounds of gold. Forty years later, a rich Spanish merchant decided to pull out the big guns and cut a fucking hole in the high cliff surrounding the lake, draining it 66-feet and drowning hundreds of people living in a nearby village in the process.
"Did you guys hear the news? I'm totally rich!"
Finally, in 1911, an American company managed to drain the entire lake, because if there's one thing America is good at, it is the total destruction of a natural resource. Sadly, the mud on the bottom of the lake proceeded to immediately harden, trapping any gold that might be left under its thick, impenetrable crust.
"Awesome! So how do I get it?"
It's full of water again these days, the gold presumably still glittering away in the mud. But before you go heading off to Colombia with your rowboat, some rope and a bucket, know that no one has ever been able to find the bulk of treasure and the Colombian government has disallowed any more draining attempts.