The proposal was submitted in response to a government call for proposals to develop hydro power. If accepted then Vaca, with a potential to develop 15 to 20MW, would be the third dam on the Macal river. The two existing structures are the Challilo on the head reaches of the river, and the 25MW Mollejon on the middle reaches.

The Vaca site is located approximately 5km from Mollejon dam. The run of river project will consist of a diversion dam built either of concrete or concrete faced rockfill, a power house, and a transmission line extending from the site to the existing 115kV hydro line.