[3] Funding for the dam was never appropriated by Congress, so in 1946 the City of Napa took on the project and built it at a cost of $550,000 plus $250,000 for the land.

The cost of laying the 36 inches (910 mm) diameter pipeline from the dam to the city of Napa was $1.7 million.

The 30 miles of pipe for the project was manufactured at the Basalt Rock Company plant located south of Napa.

Once the lake is full, water drains from a spillway causing potential flooding dangers downstream.

Hennessey was a local civic leader who played a role in the development of the Conn Valley reservoir.