Because the 4th of July is on a Saturday this year, Friday July 3rd is the paid holiday. Staff should not work that day.
https://www.umsystem.edu/ums/rules/hrm/hr400/hr401
HR-401 Holidays
Summary
The following days have been designated as official University holidays: New Year’s Day, Martin Luther King Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and the Friday following, Christmas Day, and other days as may be designated by the President. Holidays are considered to extend over a 24-hour period. When a holiday falls on Saturday, the preceding Friday is observed. When a holiday falls on Sunday, the following Monday is observed. Official holidays occurring during a vacation period are not counted against vacation time.