The California Democratic Party agreed to settle three lawsuits at a cost of more than $2.9 million in an attempt to put to rest a scandal involving alleged harassment and misconduct by its former chairman.

In one of the cases involving three plaintiffs—Tina McKinnor, the party’s former operations director; John Vigna, its former communications director; and Spencer Dayton, an activist—who alleged sexual assault, harassment and racial discrimination, the state Democratic Party is paying more than $1 million to settle, according...