Facebook usage is out of control

Karen just took over a unit that seems to be somewhat out of control. She has been tasked with cleaning up the Department. She will work on team and morale building later, but first she wants to be sure that some basic management controls are in place. These are some areas that she is considering working on.
€“It is rumored that several of the younger workers are on drugs; two have peace officer status and two are clerical staff. It seems likely, but it is unclear whether it is marijuana or drugs perceived to be even more problematic.
€“At least one employee (with peace officer status) appears to have symptoms of drinking during working hours.
€“One employee has written letters to the editor twice. The first letter complained that the need for additional funding for the agency was giving risk to serious public risks because the staffing was insufficient. The second letter stated that management practices were woefully incompetent and criticized the agency head by name saying it was time for her to step down.
€“Clerical staff are using the internet for personal use. Facebook usage is out of control. Staff have informally asserted privacy rights.
Discuss how you would proceed carefully but energetically as a manager, using the widest scope of your legal authority without exceeding normal legal bounds.