In 2010, over 100 CEOs in the United States founded the nonprofit organization, Change the Equation. What equation did they want to change? The gap between the demand for STEM employees and the supply of STEM graduates. But that mission has now broadened to making all K-12 students STEM-literate.
Since then, Change the Equation has been funding STEMworks, programs to raise the math and science abilities of children and youth. The website provides full details of the programs that are searchable by audience, age, and program type. There are plenty of high school workshops that could be done as a summer camp to prepare students for STEM curricula. Applications are accepted up through April 15 (except for a few states). These might be worth looking at as a partnership between your library and a STEM department.