Octopuses and fresh water do not mix. Therefore, you will not find any in Colorado lakes... Well, you shouldn't anyway.
According to 9News, a 5-year-old found an octopus at Boyd Lake State Park a couple weeks ago, and then his family found two more. What the octopuses were doing there is not known.
There are two theories about what happened. The first is that someone was keeping the octopuses as pets, and wanted to get rid of them in the lake.
The other is that someone was illegally dumping the dead octopuses.
Either way, whoever was responsible could be fined or lose their fishing license (if angling was the goal).