Can both fresh water and salt water flow from the same spring?

Jeremiah 6:7
As a well gushes its water, so she pours out her evil. Violence and destruction resound in her; sickness and wounds are ever before Me.

James 3:10
Out of the same mouth come blessing and cursing. My brothers, this should not be!

James 3:12
My brothers, can a fig tree grow olives, or a grapevine bear figs? Neither can a salt spring produce fresh water.

Does a fountain send forth at the same place sweet water and bitter?