Red Water (2003) on Netflix

In Louisiana, the fisherman John Sanders is near to lose his boat to the bank when his ex-wife Kelli Raymond that works in environment research and the arrogant son of her boss Gene Bradley offer an amount for him to help their company in a drilling operation in the river. Meanwhile a freshwater shark is attacking people in the area. When they arrive in the site, they see an anchored boat and they believe that belong to their competitors from the Global Oil Company. However they are dangerous criminals that are seeking a large amount of stolen money that is hidden in the bottom of the river. Gene confronts the mobsters and the group is threatened by the gangsters.