H-1B is no help there - they work for less than Americans and drive down salaries.
Most H1-B are required to work at a prevailing wage. In my experience with programmers it is at or above the level I would have paid an America if I could have found one.
But my daughter is a chemist. Chemist lab workers and software testers are full of Indian and Pakistani H1-B workers who flood the market and undoubtedly lower wages in both areas. My daughter could make more waiting tables than working in a lab as a chemist.