But you could have picked anyone of hundreds of other artificial lakes already in California. Ones that are deeper, with clean water instead of runoff.
You could also compare it to the Dead Sea, another body of water with no outlet.
The Salton Sea is already an ecological issue in terms of the run off and salinity you mentioned. Additionally there are economic concerns.
One of the plans is to use local geothermal power for desalination. Importing saltwater to freshwater lakes would disrupt ecosystems. Depth wouldn't necessarily be an advantage if we are are looking for evaporation.
But you could have picked anyone of hundreds of other artificial lakes already in California. Ones that are deeper, with clean water instead of runoff.
You could also compare it to the Dead Sea, another body of water with no outlet.